criyle/codenet-compile-errors huggingface dataset:
Language: C++

#include <iostream>
#include <string>
#include <vector>
using namespace std;

void func149c(){
    int N;
    cin >> N;

    while (!prime(N)) N++;
    cout << N << "\n";
}

int main()
{
  func149c();
  return 0;
}

Compiler output:
a.cc: In function 'void func149c()':
a.cc:10:13: error: 'prime' was not declared in this scope
   10 |     while (!prime(N)) N++;
      |             ^~~~~
Language: C++

#include <bits/stdc++.h>
using namespace std;
typedef pair<int,int> P;
typedef long long ll;
typedef long double ld;
const int inf=1e9+7;
const ll longinf=1LL<<60;
#define REP(i,m,n) for(int i=(int)(m) ; i < (int) (n) ; ++i )
#define rep(i,n) REP(i,0,n)
#define F first
#define S second

const int mx=100010;
const ll mod=1e9+7;


int main(){
  string n,q;
  cin >> n >> q;
  cout << q<<s << endl;
  return 0;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:20:14: error: 's' was not declared in this scope
   20 |   cout << q<<s << endl;
      |              ^
Language: C++

#include <bits/stdc++.h>
using namespace std;

int main(){
  string S,T;
  cin>>S>>T;
  cout<<T<<S<<emdl;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:7:15: error: 'emdl' was not declared in this scope
    7 |   cout<<T<<S<<emdl;
      |               ^~~~
Language: Java

import java.util.Scanner;
public class Main{
    public static void main(String[]args){
        Scanner scan = new Scanner(System.in);
        String s,t;
        s=scan.next();
        t=scan.next();
        System.out.println(s+t);
}

Compiler output:
Main.java:9: error: reached end of file while parsing
}
 ^
1 error
Language: Java

import java.util.*;

public class Main{
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    long A = sc.nextLong();
    long B = sc.nextLomg();
    long K = sc.nextLong();
    
    if(K <= A){
      A = A - K;
    }else if(A < K || K <= A + B){
      B = B - (K -A);
      A = 0;
    }else if(A + B <= K){
      A = 0;
      B = 0;
    }
    System.out.println(A + " " + B);
}
}


Compiler output:
Main.java:7: error: cannot find symbol
    long B = sc.nextLomg();
               ^
  symbol:   method nextLomg()
  location: variable sc of type Scanner
1 error
Language: C++

#include <bits/stdc++>
#define MAXN 105
using namespace std;

int main(void)
{
    char s[MAXN], t[MAXN];
    scanf("%s %s", s, t);
    printf("%s%s", t, s);
    cout << s;
    return 0;
}



Compiler output:
a.cc:1:10: fatal error: bits/stdc++: No such file or directory
    1 | #include <bits/stdc++>
      |          ^~~~~~~~~~~~~
compilation terminated.
Language: C++

#include<bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define Rep(i,s,n) for(int i=s;i<n;i++)
typedef long long int ll;
typedef pair<int, int> P;
typedef long double ld;
typedef first fi;
typedef second se;
void ans(bool x){if(x) cout<<"Yes"<<endl;else cout<<"No"<<endl;}

const ll INF=1001001001;

int main(){
  string A,B;
  cin>>A>>B;
  cout<<B<<A<<endl;
}

Compiler output:
a.cc:8:9: error: 'first' does not name a type
    8 | typedef first fi;
      |         ^~~~~
a.cc:9:9: error: 'second' does not name a type
    9 | typedef second se;
      |         ^~~~~~
Language: C++

#include<bits/stdc++.h>
int main{std::string s,t;std::cin>>s>>t;std::cout<<t<<s<<endl;}

Compiler output:
a.cc:2:5: error: cannot declare '::main' to be a global variable
    2 | int main{std::string s,t;std::cin>>s>>t;std::cout<<t<<s<<endl;}
      |     ^~~~
a.cc:2:22: error: expected primary-expression before 's'
    2 | int main{std::string s,t;std::cin>>s>>t;std::cout<<t<<s<<endl;}
      |                      ^
a.cc:2:22: error: expected '}' before 's'
    2 | int main{std::string s,t;std::cin>>s>>t;std::cout<<t<<s<<endl;}
      |         ~            ^
a.cc:2:31: error: 'cin' in namespace 'std' does not name a type
    2 | int main{std::string s,t;std::cin>>s>>t;std::cout<<t<<s<<endl;}
      |                               ^~~
In file included from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:146,
                 from a.cc:1:
/usr/include/c++/14/iostream:62:18: note: 'std::cin' declared here
   62 |   extern istream cin;           ///< Linked to standard input
      |                  ^~~
a.cc:2:46: error: 'cout' in namespace 'std' does not name a type
    2 | int main{std::string s,t;std::cin>>s>>t;std::cout<<t<<s<<endl;}
      |                                              ^~~~
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:2:63: error: expected declaration before '}' token
    2 | int main{std::string s,t;std::cin>>s>>t;std::cout<<t<<s<<endl;}
      |                                                               ^
Language: C++

#include<bits/stdc++.h>
int main{string s,t;std::cin>>s>>t;std::cout<<t<<s<<endl;}

Compiler output:
a.cc:2:5: error: cannot declare '::main' to be a global variable
    2 | int main{string s,t;std::cin>>s>>t;std::cout<<t<<s<<endl;}
      |     ^~~~
a.cc:2:10: error: 'string' was not declared in this scope
    2 | int main{string s,t;std::cin>>s>>t;std::cout<<t<<s<<endl;}
      |          ^~~~~~
a.cc:2:10: note: suggested alternatives:
In file included from /usr/include/c++/14/string:41,
                 from /usr/include/c++/14/bitset:52,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:52,
                 from a.cc:1:
/usr/include/c++/14/bits/stringfwd.h:77:33: note:   'std::string'
   77 |   typedef basic_string<char>    string;
      |                                 ^~~~~~
/usr/include/c++/14/string:76:11: note:   'std::pmr::string'
   76 |     using string    = basic_string<char>;
      |           ^~~~~~
a.cc:2:17: error: expected '}' before 's'
    2 | int main{string s,t;std::cin>>s>>t;std::cout<<t<<s<<endl;}
      |         ~       ^
a.cc:2:26: error: 'cin' in namespace 'std' does not name a type
    2 | int main{string s,t;std::cin>>s>>t;std::cout<<t<<s<<endl;}
      |                          ^~~
In file included from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:146:
/usr/include/c++/14/iostream:62:18: note: 'std::cin' declared here
   62 |   extern istream cin;           ///< Linked to standard input
      |                  ^~~
a.cc:2:41: error: 'cout' in namespace 'std' does not name a type
    2 | int main{string s,t;std::cin>>s>>t;std::cout<<t<<s<<endl;}
      |                                         ^~~~
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:2:58: error: expected declaration before '}' token
    2 | int main{string s,t;std::cin>>s>>t;std::cout<<t<<s<<endl;}
      |                                                          ^
Language: C++

#include<iostream>
int main{string s,t;std::cin>>s>>t;std::cout<<t<<s<<endl;}

Compiler output:
a.cc:2:5: error: cannot declare '::main' to be a global variable
    2 | int main{string s,t;std::cin>>s>>t;std::cout<<t<<s<<endl;}
      |     ^~~~
a.cc:2:10: error: 'string' was not declared in this scope
    2 | int main{string s,t;std::cin>>s>>t;std::cout<<t<<s<<endl;}
      |          ^~~~~~
a.cc:2:10: note: suggested alternatives:
In file included from /usr/include/c++/14/iosfwd:41,
                 from /usr/include/c++/14/ios:40,
                 from /usr/include/c++/14/ostream:40,
                 from /usr/include/c++/14/iostream:41,
                 from a.cc:1:
/usr/include/c++/14/bits/stringfwd.h:77:33: note:   'std::string'
   77 |   typedef basic_string<char>    string;
      |                                 ^~~~~~
In file included from /usr/include/c++/14/bits/locale_classes.h:40,
                 from /usr/include/c++/14/bits/ios_base.h:41,
                 from /usr/include/c++/14/ios:44:
/usr/include/c++/14/string:76:11: note:   'std::pmr::string'
   76 |     using string    = basic_string<char>;
      |           ^~~~~~
a.cc:2:17: error: expected '}' before 's'
    2 | int main{string s,t;std::cin>>s>>t;std::cout<<t<<s<<endl;}
      |         ~       ^
a.cc:2:26: error: 'cin' in namespace 'std' does not name a type
    2 | int main{string s,t;std::cin>>s>>t;std::cout<<t<<s<<endl;}
      |                          ^~~
/usr/include/c++/14/iostream:62:18: note: 'std::cin' declared here
   62 |   extern istream cin;           ///< Linked to standard input
      |                  ^~~
a.cc:2:41: error: 'cout' in namespace 'std' does not name a type
    2 | int main{string s,t;std::cin>>s>>t;std::cout<<t<<s<<endl;}
      |                                         ^~~~
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:2:58: error: expected declaration before '}' token
    2 | int main{string s,t;std::cin>>s>>t;std::cout<<t<<s<<endl;}
      |                                                          ^
Language: C++

#include<string>
#include<iostream>

int main(){
  string s,t;
  cin>>s>>t;
  cout<<t<<s<<endl;
 return 0; 
}

Compiler output:
a.cc: In function 'int main()':
a.cc:5:3: error: 'string' was not declared in this scope
    5 |   string s,t;
      |   ^~~~~~
a.cc:5:3: note: suggested alternatives:
In file included from /usr/include/c++/14/string:41,
                 from a.cc:1:
/usr/include/c++/14/bits/stringfwd.h:77:33: note:   'std::string'
   77 |   typedef basic_string<char>    string;
      |                                 ^~~~~~
/usr/include/c++/14/string:76:11: note:   'std::pmr::string'
   76 |     using string    = basic_string<char>;
      |           ^~~~~~
a.cc:6:3: error: 'cin' was not declared in this scope; did you mean 'std::cin'?
    6 |   cin>>s>>t;
      |   ^~~
      |   std::cin
In file included from a.cc:2:
/usr/include/c++/14/iostream:62:18: note: 'std::cin' declared here
   62 |   extern istream cin;           ///< Linked to standard input
      |                  ^~~
a.cc:6:8: error: 's' was not declared in this scope
    6 |   cin>>s>>t;
      |        ^
a.cc:6:11: error: 't' was not declared in this scope; did you mean 'tm'?
    6 |   cin>>s>>t;
      |           ^
      |           tm
a.cc:7:3: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
    7 |   cout<<t<<s<<endl;
      |   ^~~~
      |   std::cout
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:7:15: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
    7 |   cout<<t<<s<<endl;
      |               ^~~~
      |               std::endl
In file included from /usr/include/c++/14/iostream:41:
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~
Language: C++

#include <bits/c++.h>
using namespace std;

int main() {
  string S,T;cin >> S >> T;
  cout << T + S << endl;
}

Compiler output:
a.cc:1:10: fatal error: bits/c++.h: No such file or directory
    1 | #include <bits/c++.h>
      |          ^~~~~~~~~~~~
compilation terminated.
Language: Java

public class main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		String s = sc.next();
		String t = sc.next();
		System.out.println(t+s);
	}
}


Compiler output:
Main.java:1: error: class main is public, should be declared in a file named main.java
public class main {
       ^
Main.java:3: error: cannot find symbol
		Scanner sc = new Scanner(System.in);
		^
  symbol:   class Scanner
  location: class main
Main.java:3: error: cannot find symbol
		Scanner sc = new Scanner(System.in);
		                 ^
  symbol:   class Scanner
  location: class main
3 errors
Language: Java


import java.util.Scanner;

public class At149 {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		String s = sc.next();
		String t = sc.next();
		System.out.println(t+s);
	}
	
}

Compiler output:
Main.java:4: error: class At149 is public, should be declared in a file named At149.java
public class At149 {
       ^
1 error
Language: C++

#include <iostream>

using namespace std;

int main()
{
  string s,t;
  cin >> s >> t;
  for ( int i = 0; i < s.lengt(); ++i )
    cout << t[i] << s[i];
  cout << "\n";
  return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:9:26: error: 'std::string' {aka 'class std::__cxx11::basic_string<char>'} has no member named 'lengt'; did you mean 'length'?
    9 |   for ( int i = 0; i < s.lengt(); ++i )
      |                          ^~~~~
      |                          length
Language: C++

#include <iostream>

using namespace std;

int main()
{
  string s,t;
  cin >> s >> t;
  for ( int i = 0; i < s.lengt(); ++i )
    cout << s[i] << t[i];
  cout << "\n";
  return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:9:26: error: 'std::string' {aka 'class std::__cxx11::basic_string<char>'} has no member named 'lengt'; did you mean 'length'?
    9 |   for ( int i = 0; i < s.lengt(); ++i )
      |                          ^~~~~
      |                          length
Language: C

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

int main(void)
{
 char T[101];
 char S[101];
 
 scanf("%s %s",T,S);
 printf("%s",strcat(S,T));
\\ printf("%s%s\n",S,T);
 return 0;
}



Compiler output:
main.c: In function 'main':
main.c:12:1: error: stray '\' in program
   12 | \\ printf("%s%s\n",S,T);
      | ^
main.c:12:2: error: stray '\' in program
   12 | \\ printf("%s%s\n",S,T);
      |  ^
Language: Java

import java.util.*;

Class Main {

        public static void main(String[] args) {
                  Scanner sc = new Scanner(System.in);
                  String S = sc.read();
                  String T = sc.read();
                  System.out.println(T + S);
        }
}

Compiler output:
Main.java:3: error: class, interface, enum, or record expected
Class Main {
^
Main.java:5: error: unnamed classes are a preview feature and are disabled by default.
        public static void main(String[] args) {
                      ^
  (use --enable-preview to enable unnamed classes)
Main.java:11: error: class, interface, enum, or record expected
}
^
3 errors
Language: C

#include<stdio.h.
int main(void){
  char S,T;
  scanf("%s %s",&S,&T);
  printf("%s%s",S,T);
  return 0;
}

Compiler output:
main.c:1:18: error: missing terminating > character
    1 | #include<stdio.h.
      |                  ^
main.c:1:9: fatal error: stdio.h.: No such file or directory
    1 | #include<stdio.h.
      |         ^
compilation terminated.
Language: C++

#include <iostream>
#include <cstring>
using namespace std;
int main() {
	string s, t;
	cin >> s >> t;
	cout <<'t'<<'t'
}


Compiler output:
a.cc: In function 'int main()':
a.cc:7:24: error: expected ';' before '}' token
    7 |         cout <<'t'<<'t'
      |                        ^
      |                        ;
    8 | }
      | ~
Language: C++

#include<iostream>
#include<vector>
#include<algorithm>
#include<string>
#include<cmath>
#include<math.h>
using namespace std;

int main(){
  string a,b;
  std::cin >> s>>t;
  std::cout << t <<s<< '\n';
  return 0;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:11:15: error: 's' was not declared in this scope
   11 |   std::cin >> s>>t;
      |               ^
a.cc:11:18: error: 't' was not declared in this scope
   11 |   std::cin >> s>>t;
      |                  ^
Language: C++

#include <cstdio>
#define MAXN 100003
using namespace std;



int main(void){

    string s1,s2;
    cin >> s1 >>s2;
    s2 += s1;
    cout << s2;
    return 0;


}


Compiler output:
a.cc: In function 'int main()':
a.cc:9:5: error: 'string' was not declared in this scope
    9 |     string s1,s2;
      |     ^~~~~~
a.cc:2:1: note: 'std::string' is defined in header '<string>'; this is probably fixable by adding '#include <string>'
    1 | #include <cstdio>
  +++ |+#include <string>
    2 | #define MAXN 100003
a.cc:10:5: error: 'cin' was not declared in this scope
   10 |     cin >> s1 >>s2;
      |     ^~~
a.cc:2:1: note: 'std::cin' is defined in header '<iostream>'; this is probably fixable by adding '#include <iostream>'
    1 | #include <cstdio>
  +++ |+#include <iostream>
    2 | #define MAXN 100003
a.cc:10:12: error: 's1' was not declared in this scope
   10 |     cin >> s1 >>s2;
      |            ^~
a.cc:10:17: error: 's2' was not declared in this scope
   10 |     cin >> s1 >>s2;
      |                 ^~
a.cc:12:5: error: 'cout' was not declared in this scope
   12 |     cout << s2;
      |     ^~~~
a.cc:12:5: note: 'std::cout' is defined in header '<iostream>'; this is probably fixable by adding '#include <iostream>'
Language: C++

//#include <cstdio>
#include <bits/stdc++>
#define MAXN 100003
using namespace std;



int main(void){

    string s1,s2;
    cin >> s1 >>s2;
    s2 += s1;
    cout << s2;
    return 0;


}


Compiler output:
a.cc:2:10: fatal error: bits/stdc++: No such file or directory
    2 | #include <bits/stdc++>
      |          ^~~~~~~~~~~~~
compilation terminated.
Language: Java

import java.util.*;
public class Main{
  public static void main(String[] args){
    Scanner sc= new Scanner(System.in);
    String a[] =sc.next();
    String b[] =sc.next();
    System.out.println(b+a);
  }
}

Compiler output:
Main.java:5: error: incompatible types: String cannot be converted to String[]
    String a[] =sc.next();
                       ^
Main.java:6: error: incompatible types: String cannot be converted to String[]
    String b[] =sc.next();
                       ^
Main.java:7: error: bad operand types for binary operator '+'
    System.out.println(b+a);
                        ^
  first type:  String[]
  second type: String[]
3 errors
Language: C++

#include <iostream>
using namespace std;
int main() {
    string s,t;
    cin>>s>>t;
    cout<<t<<<<endl;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:6:14: error: expected primary-expression before '<<' token
    6 |     cout<<t<<<<endl;
      |              ^~
Language: C++

#include<iostream>
#include<bits/stdc++.h>
#include<string>
using namespace std;
int main()
{
string t,s;
  cin>>s>>t;
  string s1+=t+s;
  cout<<s1;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:9:12: error: expected initializer before '+=' token
    9 |   string s1+=t+s;
      |            ^~
a.cc:10:9: error: 's1' was not declared in this scope; did you mean 's'?
   10 |   cout<<s1;
      |         ^~
      |         s
Language: C++

#include<bits/stdc++.h>

using namespaace std;

int main()
{
sting s ,t;
  cin>>s>>t;
  cout<<t+s<<endl;
 return 0; 
}

Compiler output:
a.cc:3:7: error: expected nested-name-specifier before 'namespaace'
    3 | using namespaace std;
      |       ^~~~~~~~~~
a.cc: In function 'int main()':
a.cc:7:1: error: 'sting' was not declared in this scope
    7 | sting s ,t;
      | ^~~~~
a.cc:8:3: error: 'cin' was not declared in this scope; did you mean 'std::cin'?
    8 |   cin>>s>>t;
      |   ^~~
      |   std::cin
In file included from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:146,
                 from a.cc:1:
/usr/include/c++/14/iostream:62:18: note: 'std::cin' declared here
   62 |   extern istream cin;           ///< Linked to standard input
      |                  ^~~
a.cc:8:8: error: 's' was not declared in this scope
    8 |   cin>>s>>t;
      |        ^
a.cc:8:11: error: 't' was not declared in this scope; did you mean 'tm'?
    8 |   cin>>s>>t;
      |           ^
      |           tm
a.cc:9:3: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
    9 |   cout<<t+s<<endl;
      |   ^~~~
      |   std::cout
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:9:14: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
    9 |   cout<<t+s<<endl;
      |              ^~~~
      |              std::endl
In file included from /usr/include/c++/14/istream:41,
                 from /usr/include/c++/14/sstream:40,
                 from /usr/include/c++/14/complex:45,
                 from /usr/include/c++/14/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:127:
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~
Language: C++

int main() {
    string  s;
    string t;
    cin >> s;
    cin >> t;
    cout << t + s;
    return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:2:5: error: 'string' was not declared in this scope
    2 |     string  s;
      |     ^~~~~~
a.cc:3:11: error: expected ';' before 't'
    3 |     string t;
      |           ^~
      |           ;
a.cc:4:5: error: 'cin' was not declared in this scope
    4 |     cin >> s;
      |     ^~~
a.cc:4:12: error: 's' was not declared in this scope
    4 |     cin >> s;
      |            ^
a.cc:5:12: error: 't' was not declared in this scope
    5 |     cin >> t;
      |            ^
a.cc:6:5: error: 'cout' was not declared in this scope
    6 |     cout << t + s;
      |     ^~~~
Language: C++

#include<bits/stdc++.h>
#define rep(i,n) for(int i=0;i<(int)(n);i++)
using namespace std;

int mian(){
  char S[110];
  char T[110];
  /*
  cin >> S >> T;
  cout<<T<<S<<endl;
  */
 scanf("%s%s",S, T);
 cout<<T<<S<<endl;
  return 0;
}

Compiler output:
/usr/bin/ld: /usr/lib/gcc/x86_64-linux-gnu/14/../../../x86_64-linux-gnu/Scrt1.o: in function `_start':
(.text+0x17): undefined reference to `main'
collect2: error: ld returned 1 exit status
Language: C++

#include <iostream>
#include <climits>
#include <algorithm>
#include <vector>
#include <map>
#include <unordered_map>
#include <set>
#include <numeric>
#include <queue>
using namespace std;
#define pb push_back
#define mp make_pair
#define vi vector<int>
#define vvi vector<vector<int>>
#define vll vector<long long>
#define vb vector<bool>
#define vs vector<string>
#define px(x) cout << x << endl
#define pfi(x) printf("%d\n", x)
#define pfs(x) printf("%s\n", x)
#define sfi(x) scanf("%d", &x)
#define sfs(x) scanf("%s", x)
#define f first
#define sec second

int main() {
    string s;
    string t;
    cin >> s >> t;

    cout << t+s << endl;
	return 0;
}#include <iostream>
#include <climits>
#include <algorithm>
#include <vector>
#include <map>
#include <unordered_map>
#include <set>
#include <numeric>
#include <queue>
using namespace std;
#define pb push_back
#define mp make_pair
#define vi vector<int>
#define vvi vector<vector<int>>
#define vll vector<long long>
#define vb vector<bool>
#define vs vector<string>
#define px(x) cout << x << endl
#define pfi(x) printf("%d\n", x)
#define pfs(x) printf("%s\n", x)
#define sfi(x) scanf("%d", &x)
#define sfs(x) scanf("%s", x)
#define f first
#define sec second

int main() {
    string s;
    string t;
    cin >> s >> t;

    cout << t+s << endl;
	return 0;
}

Compiler output:
a.cc:33:2: error: stray '#' in program
   33 | }#include <iostream>
      |  ^
a.cc:33:3: error: 'include' does not name a type
   33 | }#include <iostream>
      |   ^~~~~~~
a.cc:58:5: error: redefinition of 'int main()'
   58 | int main() {
      |     ^~~~
a.cc:26:5: note: 'int main()' previously defined here
   26 | int main() {
      |     ^~~~
Language: Java


public class contest_149_a {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ

		String S;
		String T;
		
		System.out.println("T"+"s");
		
	}

}


Compiler output:
Main.java:2: error: class contest_149_a is public, should be declared in a file named contest_149_a.java
public class contest_149_a {
       ^
1 error
Language: C++

#include <bits/stdc++.h>
using namespace std;

int main() {
  stirng S, T;
  cin >> S >> T;
  cout << T << S << endl;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:5:3: error: 'stirng' was not declared in this scope
    5 |   stirng S, T;
      |   ^~~~~~
a.cc:6:10: error: 'S' was not declared in this scope
    6 |   cin >> S >> T;
      |          ^
a.cc:6:15: error: 'T' was not declared in this scope
    6 |   cin >> S >> T;
      |               ^
Language: C++

#include <iostream>
#include <string>
using namespase std;

int main(){
  string s, t;
  cin >> s >> t;
  cout << t + s;
}

Compiler output:
a.cc:3:7: error: expected nested-name-specifier before 'namespase'
    3 | using namespase std;
      |       ^~~~~~~~~
a.cc: In function 'int main()':
a.cc:6:3: error: 'string' was not declared in this scope
    6 |   string s, t;
      |   ^~~~~~
a.cc:6:3: note: suggested alternatives:
In file included from /usr/include/c++/14/iosfwd:41,
                 from /usr/include/c++/14/ios:40,
                 from /usr/include/c++/14/ostream:40,
                 from /usr/include/c++/14/iostream:41,
                 from a.cc:1:
/usr/include/c++/14/bits/stringfwd.h:77:33: note:   'std::string'
   77 |   typedef basic_string<char>    string;
      |                                 ^~~~~~
In file included from /usr/include/c++/14/bits/locale_classes.h:40,
                 from /usr/include/c++/14/bits/ios_base.h:41,
                 from /usr/include/c++/14/ios:44:
/usr/include/c++/14/string:76:11: note:   'std::pmr::string'
   76 |     using string    = basic_string<char>;
      |           ^~~~~~
a.cc:7:3: error: 'cin' was not declared in this scope; did you mean 'std::cin'?
    7 |   cin >> s >> t;
      |   ^~~
      |   std::cin
/usr/include/c++/14/iostream:62:18: note: 'std::cin' declared here
   62 |   extern istream cin;           ///< Linked to standard input
      |                  ^~~
a.cc:7:10: error: 's' was not declared in this scope
    7 |   cin >> s >> t;
      |          ^
a.cc:7:15: error: 't' was not declared in this scope; did you mean 'tm'?
    7 |   cin >> s >> t;
      |               ^
      |               tm
a.cc:8:3: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
    8 |   cout << t + s;
      |   ^~~~
      |   std::cout
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
Language: Java

import java.util.*;
import java.util.Map.Entry;
 
 
 class Main {
	 static int mod =  (int) (Math.pow(10,9)+7);
	 static List<ArrayList<Integer>>  list = new ArrayList<ArrayList<Integer>>();
    public static void main(String[] args) {
    
        Scanner sc = new Scanner(System.in);
        String a = sc.next();
        String b = sc.next();
        
        System.out.println(a+b);
        		
    }

Compiler output:
Main.java:16: error: reached end of file while parsing
    }
     ^
1 error
Language: C++

#include<iostream>
#includue<string>
using namespace std;

int main(){
  string s, t;
  cin >> s >> t;
  cout << t << s << endl;
  return 0;
}

Compiler output:
a.cc:2:2: error: invalid preprocessing directive #includue; did you mean #include?
    2 | #includue<string>
      |  ^~~~~~~~
      |  include
Language: C++

#include<iostram>
using namespace std;

int main(){
	string s,t;
	cin >> s >> t;
	
	cout << s << t <<endl;
	return 0;
}

Compiler output:
a.cc:1:9: fatal error: iostram: No such file or directory
    1 | #include<iostram>
      |         ^~~~~~~~~
compilation terminated.
Language: C++

#include<iostream>
using namespace std;
int main(){
  string S,T;
  cin >> S >> T;
  cout << S << T endl;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:6:17: error: expected ';' before 'endl'
    6 |   cout << S << T endl;
      |                 ^~~~~
      |                 ;
Language: C++

#include <bits/stdc++.h>
using namespace std;

int main()
{


        string S;
        stirng T;

        cin >> S >> T;

        cout << T << S << endl;








}


Compiler output:
a.cc: In function 'int main()':
a.cc:9:9: error: 'stirng' was not declared in this scope
    9 |         stirng T;
      |         ^~~~~~
a.cc:11:21: error: 'T' was not declared in this scope
   11 |         cin >> S >> T;
      |                     ^
Language: C++

#include<iostream>
using namespace std;
int main()
{
  string S;
  string T;
  cin >> S >> T;
  cout << TS;
    return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:8:11: error: 'TS' was not declared in this scope; did you mean 'T'?
    8 |   cout << TS;
      |           ^~
      |           T
Language: C++

#include<iostream>
using namespace std;
int main()
{
  string S;
  string T;
  cin >> S >> T;
  cout << TS;
  
    return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:8:11: error: 'TS' was not declared in this scope; did you mean 'T'?
    8 |   cout << TS;
      |           ^~
      |           T
Language: C++

a = str(input())
b = str(input())
a,b = b,a
print(a+b)
# a = 2
# b =  1


Compiler output:
a.cc:5:3: error: invalid preprocessing directive #a
    5 | # a = 2
      |   ^
a.cc:6:3: error: invalid preprocessing directive #b
    6 | # b =  1
      |   ^
a.cc:1:1: error: 'a' does not name a type
    1 | a = str(input())
      | ^
Language: C

import java.util.Scanner;

class Main {
	public static void main(String[] args) {
		final Scanner sc = new Scanner(System.in);
		final String S = sc.next();
		final String T = sc.next();
		System.out.print(T);
		System.out.println(S);
	}
}

Compiler output:
main.c:1:1: error: unknown type name 'import'
    1 | import java.util.Scanner;
      | ^~~~~~
main.c:1:12: error: expected '=', ',', ';', 'asm' or '__attribute__' before '.' token
    1 | import java.util.Scanner;
      |            ^
main.c:3:1: error: unknown type name 'class'
    3 | class Main {
      | ^~~~~
main.c:3:12: error: expected '=', ',', ';', 'asm' or '__attribute__' before '{' token
    3 | class Main {
      |            ^
Language: C++

#include<bits/stdc++.h>
using namespace std;
int main(){
 stirng S,T;
 cin >> S >> T;
 cout << T << S << endl;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:4:2: error: 'stirng' was not declared in this scope
    4 |  stirng S,T;
      |  ^~~~~~
a.cc:5:9: error: 'S' was not declared in this scope
    5 |  cin >> S >> T;
      |         ^
a.cc:5:14: error: 'T' was not declared in this scope
    5 |  cin >> S >> T;
      |              ^
Language: C++

#include<bits/stdc++.h>
unding namespace std;
int main(){
 stirng S,T;
 cin >> S >> T;
 cout << T << S << endl;
}


Compiler output:
a.cc:2:1: error: 'unding' does not name a type
    2 | unding namespace std;
      | ^~~~~~
a.cc: In function 'int main()':
a.cc:4:2: error: 'stirng' was not declared in this scope
    4 |  stirng S,T;
      |  ^~~~~~
a.cc:5:2: error: 'cin' was not declared in this scope; did you mean 'std::cin'?
    5 |  cin >> S >> T;
      |  ^~~
      |  std::cin
In file included from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:146,
                 from a.cc:1:
/usr/include/c++/14/iostream:62:18: note: 'std::cin' declared here
   62 |   extern istream cin;           ///< Linked to standard input
      |                  ^~~
a.cc:5:9: error: 'S' was not declared in this scope
    5 |  cin >> S >> T;
      |         ^
a.cc:5:14: error: 'T' was not declared in this scope
    5 |  cin >> S >> T;
      |              ^
a.cc:6:2: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
    6 |  cout << T << S << endl;
      |  ^~~~
      |  std::cout
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:6:20: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
    6 |  cout << T << S << endl;
      |                    ^~~~
      |                    std::endl
In file included from /usr/include/c++/14/istream:41,
                 from /usr/include/c++/14/sstream:40,
                 from /usr/include/c++/14/complex:45,
                 from /usr/include/c++/14/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:127:
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~
Language: C++

#include<bits/stdc++.h>
unding namespace std;
main(){
 stirng S,T;
 cin >> S >> T;
 cout << T << S << endl;
}


Compiler output:
a.cc:2:1: error: 'unding' does not name a type
    2 | unding namespace std;
      | ^~~~~~
a.cc:3:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
    3 | main(){
      | ^~~~
a.cc: In function 'int main()':
a.cc:4:2: error: 'stirng' was not declared in this scope
    4 |  stirng S,T;
      |  ^~~~~~
a.cc:5:2: error: 'cin' was not declared in this scope; did you mean 'std::cin'?
    5 |  cin >> S >> T;
      |  ^~~
      |  std::cin
In file included from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:146,
                 from a.cc:1:
/usr/include/c++/14/iostream:62:18: note: 'std::cin' declared here
   62 |   extern istream cin;           ///< Linked to standard input
      |                  ^~~
a.cc:5:9: error: 'S' was not declared in this scope
    5 |  cin >> S >> T;
      |         ^
a.cc:5:14: error: 'T' was not declared in this scope
    5 |  cin >> S >> T;
      |              ^
a.cc:6:2: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
    6 |  cout << T << S << endl;
      |  ^~~~
      |  std::cout
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:6:20: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
    6 |  cout << T << S << endl;
      |                    ^~~~
      |                    std::endl
In file included from /usr/include/c++/14/istream:41,
                 from /usr/include/c++/14/sstream:40,
                 from /usr/include/c++/14/complex:45,
                 from /usr/include/c++/14/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:127:
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~
Language: Java

import java.util.Scanner;

public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		
		String s = sc.nextInt();
		String t = sc.nextInt();

		System.out.println(s+t);
	}
}

Compiler output:
Main.java:7: error: incompatible types: int cannot be converted to String
		String s = sc.nextInt();
		                     ^
Main.java:8: error: incompatible types: int cannot be converted to String
		String t = sc.nextInt();
		                     ^
2 errors
Language: C++

#include<stdio.h>
#include<string.h>
int main()
{
    char s[105],t[105];
    gets(s);
    gets(t);
    printf("%s",t);
    printf("%s\n",s);
}


Compiler output:
a.cc: In function 'int main()':
a.cc:6:5: error: 'gets' was not declared in this scope; did you mean 'getw'?
    6 |     gets(s);
      |     ^~~~
      |     getw
Language: C++

#include<iostream>
using nmaespace std;
int main(){
  	string s,t;
  	cin >> s >> t;
  	cout << t << s << endl;
	return 0;
}

Compiler output:
a.cc:2:7: error: expected nested-name-specifier before 'nmaespace'
    2 | using nmaespace std;
      |       ^~~~~~~~~
a.cc: In function 'int main()':
a.cc:4:9: error: 'string' was not declared in this scope
    4 |         string s,t;
      |         ^~~~~~
a.cc:4:9: note: suggested alternatives:
In file included from /usr/include/c++/14/iosfwd:41,
                 from /usr/include/c++/14/ios:40,
                 from /usr/include/c++/14/ostream:40,
                 from /usr/include/c++/14/iostream:41,
                 from a.cc:1:
/usr/include/c++/14/bits/stringfwd.h:77:33: note:   'std::string'
   77 |   typedef basic_string<char>    string;
      |                                 ^~~~~~
In file included from /usr/include/c++/14/bits/locale_classes.h:40,
                 from /usr/include/c++/14/bits/ios_base.h:41,
                 from /usr/include/c++/14/ios:44:
/usr/include/c++/14/string:76:11: note:   'std::pmr::string'
   76 |     using string    = basic_string<char>;
      |           ^~~~~~
a.cc:5:9: error: 'cin' was not declared in this scope; did you mean 'std::cin'?
    5 |         cin >> s >> t;
      |         ^~~
      |         std::cin
/usr/include/c++/14/iostream:62:18: note: 'std::cin' declared here
   62 |   extern istream cin;           ///< Linked to standard input
      |                  ^~~
a.cc:5:16: error: 's' was not declared in this scope
    5 |         cin >> s >> t;
      |                ^
a.cc:5:21: error: 't' was not declared in this scope; did you mean 'tm'?
    5 |         cin >> s >> t;
      |                     ^
      |                     tm
a.cc:6:9: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
    6 |         cout << t << s << endl;
      |         ^~~~
      |         std::cout
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:6:27: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
    6 |         cout << t << s << endl;
      |                           ^~~~
      |                           std::endl
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~
Language: C++

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef vector<long long> vll;
typedef vector<pair<int,int>> vp;
typedef pair<int,int> pii;
#define INF (int)(1e9)
#define MAXX 1.1529215e+18
#define inf 999999
#define EPS (1e-7)
#define rep(i,n) for(int i=0; i<(int)(n);i++)
#define REP(i,n) for(int i=1;i<=(int)(n);i++)
#define FOR(i,k,n) for(int i=(k);i<(int)(n);i++)
#define ALL(a)  a.begin(),a.end()
#define RALL(a) a.begin(),a.end(),greater<int>()
#define ROT(a) a.begin(),a.begin()+1,a.end()
#define RROT(a) a.begin(),a.end()-1,a.end()
#define PB push_back
#define MP make_pair
#define PI acos(-1.0)
#define sz(a) a.size()
const ll MOD = 1e9+7;
const int MAX = 10000000;
template<typename T1, typename T2> inline bool chmin(T1 &a, T2 b) { if (a > b) { a = b; return 1; } return 0; }
template<typename T1, typename T2> inline bool chmax(T1 &a, T2 b) { if (a < b) { a = b; return 1; } return 0; }
template<typename T> T gcd(T a, T b) { if (b == 0) return a; return gcd(b, a % b); }
//cout << 'H' << endl;
//next_permutation(ALL(p));
//typedef priority_que<int> pque;//これは大きい順
//typedef priority_que<int, vector<int>, greater<int>> pque;//これは小さい順


int main(){
	char s[],t[];
	cin >> s >> t;
	cout << s << t << endl;

  return 0;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:34:14: error: storage size of 's' isn't known
   34 |         char s[],t[];
      |              ^
a.cc:34:18: error: storage size of 't' isn't known
   34 |         char s[],t[];
      |                  ^
Language: C++

using System;

class MainClass
{
    public static void Main(string[] args)
    {
        var st = Console.ReadLine().Split();
        Console.WriteLine(st[1] + st[0]);
    }
}


Compiler output:
a.cc:1:7: error: expected nested-name-specifier before 'System'
    1 | using System;
      |       ^~~~~~
a.cc:5:11: error: expected ':' before 'static'
    5 |     public static void Main(string[] args)
      |           ^~~~~~~
      |           :
a.cc:5:29: error: 'string' has not been declared
    5 |     public static void Main(string[] args)
      |                             ^~~~~~
a.cc:5:38: error: expected ',' or '...' before 'args'
    5 |     public static void Main(string[] args)
      |                                      ^~~~
a.cc:10:2: error: expected ';' after class definition
   10 | }
      |  ^
      |  ;
a.cc: In static member function 'static void MainClass::Main(int*)':
a.cc:7:9: error: 'var' was not declared in this scope
    7 |         var st = Console.ReadLine().Split();
      |         ^~~
a.cc:8:9: error: 'Console' was not declared in this scope
    8 |         Console.WriteLine(st[1] + st[0]);
      |         ^~~~~~~
a.cc:8:27: error: 'st' was not declared in this scope; did you mean 'std'?
    8 |         Console.WriteLine(st[1] + st[0]);
      |                           ^~
      |                           std
Language: C++

#include <iostream>
using namespace std,
int main(){
  int s,t;
  cin >> s >>t;
  if(s%t==0){
    

Compiler output:
a.cc:2:20: error: expected ';' before ',' token
    2 | using namespace std,
      |                    ^
      |                    ;
a.cc:2:20: error: expected unqualified-id before ',' token
a.cc:3:1: error: expected unqualified-id before 'int'
    3 | int main(){
      | ^~~
Language: C++

#include <bits/stdc++.h>
using namespace std;

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
  	long long a,b,k;
  	cin>>a>>b>>k;
  
   if(k>=a+b){a=0;b=0;}
  else if{
  	a-=k;
  if(a<0){
    b+=a;
    a=0;
  }
  }
  
  cout<<a<<" "<<b;

  	
    return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:12:10: error: expected '(' before '{' token
   12 |   else if{
      |          ^
      |          (
Language: C++

#include <bits/stdc++.h>
using namespace std;

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
  
  string a,b
    cin>>a>>b;
  cout<<b+a;
    return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:10:5: error: expected initializer before 'cin'
   10 |     cin>>a>>b;
      |     ^~~
a.cc:11:9: error: 'b' was not declared in this scope
   11 |   cout<<b+a;
      |         ^
Language: C++

#inclde<bits/stdc++.h>
using namespace std;

int main() {
  string s,t;
  cin >> s >> t;
  cout << t << s << endl;
}

Compiler output:
a.cc:1:2: error: invalid preprocessing directive #inclde; did you mean #include?
    1 | #inclde<bits/stdc++.h>
      |  ^~~~~~
      |  include
a.cc: In function 'int main()':
a.cc:5:3: error: 'string' was not declared in this scope
    5 |   string s,t;
      |   ^~~~~~
a.cc:1:1: note: 'std::string' is defined in header '<string>'; this is probably fixable by adding '#include <string>'
  +++ |+#include <string>
    1 | #inclde<bits/stdc++.h>
a.cc:6:3: error: 'cin' was not declared in this scope
    6 |   cin >> s >> t;
      |   ^~~
a.cc:1:1: note: 'std::cin' is defined in header '<iostream>'; this is probably fixable by adding '#include <iostream>'
  +++ |+#include <iostream>
    1 | #inclde<bits/stdc++.h>
a.cc:6:10: error: 's' was not declared in this scope
    6 |   cin >> s >> t;
      |          ^
a.cc:6:15: error: 't' was not declared in this scope
    6 |   cin >> s >> t;
      |               ^
a.cc:7:3: error: 'cout' was not declared in this scope
    7 |   cout << t << s << endl;
      |   ^~~~
a.cc:7:3: note: 'std::cout' is defined in header '<iostream>'; this is probably fixable by adding '#include <iostream>'
a.cc:7:21: error: 'endl' was not declared in this scope
    7 |   cout << t << s << endl;
      |                     ^~~~
a.cc:1:1: note: 'std::endl' is defined in header '<ostream>'; this is probably fixable by adding '#include <ostream>'
  +++ |+#include <ostream>
    1 | #inclde<bits/stdc++.h>
Language: C

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<math.h>
#define FOR(n) for(int i=0;i<n;i++)
#define FORJ(n) for(int j=0;j<n;j++)
#define PRN(n) printf("%d\n",n)
#define PRF(n) printf("%lf\n",n)
#define PRL(n) printf("%lld\n",n)
#define PRS(s) printf("%s\n",s)
#define PRC(c) printf("%c",c)
#define INF 10000000000
#define mod 1000000007
#define X 1000000
typedef long long int ll;
ll finv[X];
ll fac[X];
ll inv[X];
ll usort(const void *a, const void *b){return *(ll*)a-*(ll*)b;}
ll dsort(const void *a, const void *b){return *(ll*)b-*(ll*)a;}
ll ssort(const void *a, const void *b){return strcmp((char*)a,(char*)b);}
ll min(ll a,ll b){
  if(a>b)return b;
  return a;
}
ll max(ll a,ll b){
  if(a>b)return a;
  return b;
}
ll z(ll a){return max(a,-a);}
ll gcd(ll a,ll b){if(!b){return a;}else{return gcd(b,a%b);}}
ll lcm(ll a,ll b){return a*b/gcd(a,b);}
ll kt(ll a){
  ll sum=0;
  while(a){
    a/=10;
    sum++;
  }
  return sum;
}
ll ks(ll a){
  ll sum=0;
  while(a){
    sum+=a%10;
    a/=10;
  }
  return sum;
}
void ppp(){
  fac[0]=fac[1]=1;
  finv[0]=finv[1]=1;
  inv[1]=1;
  for (int i=2;i<X;i++){
    fac[i]=fac[i-1]*i%mod;
    inv[i]=mod-inv[mod%i]*(mod/i)%mod;
    finv[i]=finv[i-1]*inv[i]%mod;
  }
}
ll nCr(int n,int k){
  return fac[n]*(finv[k]*finv[n-k]%mod)%mod;
}
int main(void){
  char s[101],t[101];
  scanf("%s %s",s,t);
  printf("%s%s\n",t,s)
  return 0;
}


Compiler output:
main.c: In function 'main':
main.c:65:23: error: expected ';' before 'return'
   65 |   printf("%s%s\n",t,s)
      |                       ^
      |                       ;
   66 |   return 0;
      |   ~~~~~~
Language: Java

import java.io.*;
import java.util.*;
import java.lang.*;
import java.math.*;

public class A {
//	public void run() throws Exception {
//		FastScanner sc = new FastScanner();
//		String t = sc.next();
//		String s = sc.next();
//		System.out.println(s + t);
//		
//	}
//	static class FastScanner {
//		public BufferedReader reader;
//		public StringTokenizer tokenizer;
//
//		public FastScanner() {
//			reader = new BufferedReader(new InputStreamReader(System.in), 32768);
//			tokenizer = null;
//		}
//
//		public String next() {
//			while (tokenizer == null || !tokenizer.hasMoreTokens()) {
//				try {
//					tokenizer = new StringTokenizer(reader.readLine());
//				} catch (IOException e) {
//					throw new RuntimeException(e);
//				}
//			}
//			return tokenizer.nextToken();
//		}
//
//		public int nextInt() {
//			return Integer.parseInt(next());
//		}
//
//		public long nextLong() {
//			return Long.parseLong(next());
//		}
//
//		public double nextDouble() {
//			return Double.parseDouble(next());
//		}
//
//		public String nextLine() {
//			try {
//				return reader.readLine();
//			} catch (IOException e) {
//				throw new RuntimeException(e);
//			}
//		}
//
//	}
	public void run() throws Exception
	{
		System.out.println("Hi");
	}
	public static void main (String[] args) throws Exception {
		new A().run();
	}
}

Compiler output:
Main.java:6: error: class A is public, should be declared in a file named A.java
public class A {
       ^
1 error
Language: Java

import java.io.*;
import java.util.*;
import java.lang.*;
import java.math.*;

public class A {
	public void run() throws Exception {
		FastScanner sc = new FastScanner();
		String t = sc.next();
		String s = sc.next();
		System.out.println(s + t);
		
	}
	static class FastScanner {
		public BufferedReader reader;
		public StringTokenizer tokenizer;

		public FastScanner() {
			reader = new BufferedReader(new InputStreamReader(System.in), 32768);
			tokenizer = null;
		}

		public String next() {
			while (tokenizer == null || !tokenizer.hasMoreTokens()) {
				try {
					tokenizer = new StringTokenizer(reader.readLine());
				} catch (IOException e) {
					throw new RuntimeException(e);
				}
			}
			return tokenizer.nextToken();
		}

		public int nextInt() {
			return Integer.parseInt(next());
		}

		public long nextLong() {
			return Long.parseLong(next());
		}

		public double nextDouble() {
			return Double.parseDouble(next());
		}

		public String nextLine() {
			try {
				return reader.readLine();
			} catch (IOException e) {
				throw new RuntimeException(e);
			}
		}

	}
	public static void main (String[] args) throws Exception {
		new A().run();
	}
}

Compiler output:
Main.java:6: error: class A is public, should be declared in a file named A.java
public class A {
       ^
1 error