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

#include<iostream>
using namespace std;
 
int main()
{
  int a,b,i;
  cin>>a>>b;
  for(i=0;i<a;i++)
  	string c[i];
  for(i=0;i<a;i++){
  		cin<<c[i]<<\n<<c[i]<<endl;
  }
  return 0;
}

Compiler output:
a.cc:11:28: error: stray '\' in program
   11 |                 cin<<c[i]<<\n<<c[i]<<endl;
      |                            ^
a.cc: In function 'int main()':
a.cc:11:22: error: 'c' was not declared in this scope
   11 |                 cin<<c[i]<<\n<<c[i]<<endl;
      |                      ^
a.cc:11:29: error: 'n' was not declared in this scope
   11 |                 cin<<c[i]<<\n<<c[i]<<endl;
      |                             ^
Language: C++

#include<iostream>
using namespace std;

int main()
{
  int a,b,i;
  cin>>a>>b;
  for(i=0;i<a;i++)
  	string c;
  for(i=0;i<a;i++){
  		cin<<s<<\n<<s;
  }
  return 0;
}
      
  

Compiler output:
a.cc:11:25: error: stray '\' in program
   11 |                 cin<<s<<\n<<s;
      |                         ^
a.cc: In function 'int main()':
a.cc:11:22: error: 's' was not declared in this scope
   11 |                 cin<<s<<\n<<s;
      |                      ^
a.cc:11:26: error: 'n' was not declared in this scope
   11 |                 cin<<s<<\n<<s;
      |                          ^
Language: C++

#include <iostream>
#include <vector>
#include <iterator>
#include <algorithm>
#include <string>
#include <map>
#include <list>
using namespace std;

int main() {
  int H,W;
  cin >> H >> W;
  char c[H][W];
  for(int i=0; i<H; ++i){
    for(int j=0; j<W; ++j){
      cin >> c[i][j];
    }
  }

  char resC[2*H][W];
  for(int i=0; i<H; ++i){
    for(int j=0; j<W; ++j){
      resC[2*i][j]=c[i][j];
      resC[2*i+1][j]=c[i][j];
    }
  }
  
  for(int i=0; i<2*H; ++i){
    for(int j=0; j<W; ++j){
      cout << resC[i][j];
    }
    cout << endl;
  }
  å
}



Compiler output:
a.cc: In function 'int main()':
a.cc:34:3: error: '\U000000e5' was not declared in this scope
   34 |   å
      |   ^
Language: C++

#include <bits/stdc++.h>
using namespace std;
 
int main() {
    
int h,w;
  cin>>h>>w;
  for(int i=0;i<h;i++){
  vector<char> vec(w);
    for(int =j=0;j<w;j++){
    cin >> vec[j];
      cout<<vec[j];
    }
    for(int =k=0;k<w;k++){
      cout <<vec[k];
    }

  
  
  }
  
}

Compiler output:
a.cc: In function 'int main()':
a.cc:10:13: error: expected unqualified-id before '=' token
   10 |     for(int =j=0;j<w;j++){
      |             ^
a.cc:10:12: error: expected ';' before '=' token
   10 |     for(int =j=0;j<w;j++){
      |            ^~
      |            ;
a.cc:10:13: error: expected primary-expression before '=' token
   10 |     for(int =j=0;j<w;j++){
      |             ^
a.cc:10:14: error: 'j' was not declared in this scope
   10 |     for(int =j=0;j<w;j++){
      |              ^
a.cc:10:21: error: expected ')' before ';' token
   10 |     for(int =j=0;j<w;j++){
      |        ~            ^
      |                     )
a.cc:10:22: error: 'j' was not declared in this scope
   10 |     for(int =j=0;j<w;j++){
      |                      ^
a.cc:14:13: error: expected unqualified-id before '=' token
   14 |     for(int =k=0;k<w;k++){
      |             ^
a.cc:14:12: error: expected ';' before '=' token
   14 |     for(int =k=0;k<w;k++){
      |            ^~
      |            ;
a.cc:14:13: error: expected primary-expression before '=' token
   14 |     for(int =k=0;k<w;k++){
      |             ^
a.cc:14:14: error: 'k' was not declared in this scope
   14 |     for(int =k=0;k<w;k++){
      |              ^
a.cc:14:21: error: expected ')' before ';' token
   14 |     for(int =k=0;k<w;k++){
      |        ~            ^
      |                     )
a.cc:14:22: error: 'k' was not declared in this scope
   14 |     for(int =k=0;k<w;k++){
      |                      ^
Language: C++

#include<iostream>
using namespace std;
int main(){
  int a,b;
  cin>>>a>>b;
  char c[105];
  for(int i=0;i<a;i++){
    cin>>c;
    printf("%s\n%s",c,c);
  }
  return 0;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:5:8: error: expected primary-expression before '>' token
    5 |   cin>>>a>>b;
      |        ^
Language: C++

#include<iostream>
using namespace std;
int main(){
  int a,b;
  cin>>>a>>b;
  string c;
  for(int i=0;i<n;i++){
    cin>>c;
    cout<<c<<c;
  }
  return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:5:8: error: expected primary-expression before '>' token
    5 |   cin>>>a>>b;
      |        ^
a.cc:7:17: error: 'n' was not declared in this scope
    7 |   for(int i=0;i<n;i++){
      |                 ^
Language: C++

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define rep(i, srt, end) for (long long i = (srt); i < (long long)(end); i++)
#define VL vector<ll>
#define VS vector<string>

int main(){
    ll N, M;
    cin >> N >> M;
    VS s(N);
    rep(i, 0, N){
        cin >> s[i];
    }
    rep(j, 0, 2*N){
        cout << s[I] << endl;
    }
    return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:16:19: error: 'I' was not declared in this scope
   16 |         cout << s[I] << endl;
      |                   ^
Language: C++

#define _GLIBCXX_DEBUG
#include <bits/stdc++.h>
using namespace std;
#define int long long
#define rep(i,n) for(int i=0;i<n;i++)
#define rep1(i,n) for(int i=1;i<=n;i++)
#define rep2(i,n) for(int i=0;i<=n;i++)
#define repr(i,a,n) for(int i=a;i<n;i++)
#define all(a) a.begin(),a.end()
#define P pair<long long,long long>
#define uni(e) e.erase(unique(e.begin(),e.end()),e.end())
#define double long double
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
int INF=1e10;
int MOD=1e9+7;
template<class T> void out(T a){cout<<a<<'\n';}
template<class T> void yesno(T b){if(b)out("yes");else out("no");}
template<class T> void YesNo(T b){if(b)out("Yes");else out("No");}
template<class T> void YESNO(T b){if(b)out("YES");else out("NO");}
template<class T> void noyes(T b){if(b)out("no");else out("yes");}
template<class T> void NoYes(T b){if(b)out("No");else out("Yes");}
template<class T> void NOYES(T b){if(b)out("NO");else out("YES");}
int keta(int a){
  double b=a;
  b=log10(b);
  int c=b;
  return c+1;
}
int kurai(int a,int b){
  int m=pow(10,b),n=pow(10,b-1);
  return (a%m)/n;
}
int ketawa(int a){
  int k=0;
  rep(i,keta(a)){
  k+=kurai(a,i+1);
  }
  return k;
}
int gcd(int a,int b){
  if(a%b==0)
    return b;
  return gcd(b,a%b);
}
int lcm(int a,int b){
    return a/gcd(a,b)*b;
}
int mid(int a,int b,int c){
  vector<int> k(3);
  k[0]=a;k[1]=b;k[2]=c;
  sort(all(k));
  return k[1];
}
bool sosuu(int a){
  bool b=1;
  if(a<=1)
    return 0;
  else{
  rep1(i,sqrt(a)-1){
  if(a%(i+1)==0)
  b=0;
  }
  return b;
  }
}
int modpow(int a,int b,int m=MOD){
 if(!b)return 1; if(b&1)return modpow(a,b-1,m)*a%m;
 int memo = modpow(a,b>>1,m);
 return memo*memo%m;
}
int fact_mod(int n) {
    int f=1; 
for(int i=2;i<n+1;i++) f=f*(i%MOD)% MOD;
    return f;
}
int mod_pow(int x,int n) {
    int res=1;
    while(n>0){
        if(n&1) res=(res*x)%MOD; 
        x=(x*x)%MOD;        
n>>=1; 
    }
    return res;
}
int c_mod(int n, int r) {
    if(r>n-r) r=n-r;
    if(r==0) return 1;
    int a=1;
    rep(i,r) 
a=a*((n-i)%MOD)%MOD;
    int b=mod_pow(fact_mod(r), MOD-2);
    return (a%MOD)*(b%MOD)%MOD;
}
signed main(){
  int a,b;
  cin>>a>>b;
 int c[a][b];
  rep(i,a)rep(j,b)
    cin>>b[i][j];
 
}


Compiler output:
a.cc: In function 'int main()':
a.cc:100:11: error: invalid types 'long long int[long long int]' for array subscript
  100 |     cin>>b[i][j];
      |           ^
Language: C++

#define _GLIBCXX_DEBUG
#include <bits/stdc++.h>
using namespace std;
#define int long long
#define rep(i,n) for(int i=0;i<n;i++)
#define rep1(i,n) for(int i=1;i<=n;i++)
#define rep2(i,n) for(int i=0;i<=n;i++)
#define repr(i,a,n) for(int i=a;i<n;i++)
#define all(a) a.begin(),a.end()
#define P pair<long long,long long>
#define uni(e) e.erase(unique(e.begin(),e.end()),e.end())
#define double long double
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
int INF=1e10;
int MOD=1e9+7;
template<class T> void out(T a){cout<<a<<'\n';}
template<class T> void yesno(T b){if(b)out("yes");else out("no");}
template<class T> void YesNo(T b){if(b)out("Yes");else out("No");}
template<class T> void YESNO(T b){if(b)out("YES");else out("NO");}
template<class T> void noyes(T b){if(b)out("no");else out("yes");}
template<class T> void NoYes(T b){if(b)out("No");else out("Yes");}
template<class T> void NOYES(T b){if(b)out("NO");else out("YES");}
int keta(int a){
  double b=a;
  b=log10(b);
  int c=b;
  return c+1;
}
int kurai(int a,int b){
  int m=pow(10,b),n=pow(10,b-1);
  return (a%m)/n;
}
int ketawa(int a){
  int k=0;
  rep(i,keta(a)){
  k+=kurai(a,i+1);
  }
  return k;
}
int gcd(int a,int b){
  if(a%b==0)
    return b;
  return gcd(b,a%b);
}
int lcm(int a,int b){
    return a/gcd(a,b)*b;
}
int mid(int a,int b,int c){
  vector<int> k(3);
  k[0]=a;k[1]=b;k[2]=c;
  sort(all(k));
  return k[1];
}
bool sosuu(int a){
  bool b=1;
  if(a<=1)
    return 0;
  else{
  rep1(i,sqrt(a)-1){
  if(a%(i+1)==0)
  b=0;
  }
  return b;
  }
}
int modpow(int a,int b,int m=MOD){
 if(!b)return 1; if(b&1)return modpow(a,b-1,m)*a%m;
 int memo = modpow(a,b>>1,m);
 return memo*memo%m;
}
int fact_mod(int n) {
    int f=1; 
for(int i=2;i<n+1;i++) f=f*(i%MOD)% MOD;
    return f;
}
int mod_pow(int x,int n) {
    int res=1;
    while(n>0){
        if(n&1) res=(res*x)%MOD; 
        x=(x*x)%MOD;        
n>>=1; 
    }
    return res;
}
int c_mod(int n, int r) {
    if(r>n-r) r=n-r;
    if(r==0) return 1;
    int a=1;
    rep(i,r) 
a=a*((n-i)%MOD)%MOD;
    int b=mod_pow(fact_mod(r), MOD-2);
    return (a%MOD)*(b%MOD)%MOD;
}
signed main(){
  int a,b;
  cin>>a>>b;
 int c[a][b];
  rep(i,a)rep(j,b)
    cin>>b[i][j];
  rep(i,2*a){
    rep(j,b){
    cout<<b[i/2][j];
    }
    cout<<' '<<endl;
  }
}

Compiler output:
a.cc: In function 'int main()':
a.cc:100:11: error: invalid types 'long long int[long long int]' for array subscript
  100 |     cin>>b[i][j];
      |           ^
a.cc:103:12: error: invalid types 'long long int[long long int]' for array subscript
  103 |     cout<<b[i/2][j];
      |            ^
Language: C++

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

#define pb(s) push_back(s)
#define ALL(v) v.begin(), v.end()
#define ALLA(arr, sz) arr, arr + sz
#define SORT(v) sort(ALL(v))
#define REVERSE(v) reverse(ALL(v))
#define SORTA(arr, sz) sort(ALLA(arr, sz))
#define REVERSEA(arr, sz) reverse(ALLA(arr, sz))

typedef long long ll;

int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    int h,w;
    cin>>h>>w;
    char grid1[h][w]={0};
    for(int i=0;i<h;++i){
        for(int j=0;j<w;++j){
            cin>>grid1[i][j];
        }
    }

    for(int i=0;i<h;++i){
        for(int j=0;j<w;++j){
            cout<<grid1[i][j]<<endl;
            cout<<grid[i][j]<<endl;
        }
    }
    
    return 0;
}



Compiler output:
a.cc: In function 'int main()':
a.cc:31:19: error: 'grid' was not declared in this scope; did you mean 'grid1'?
   31 |             cout<<grid[i][j]<<endl;
      |                   ^~~~
      |                   grid1
Language: C++

//#include <bits/stdc++.h>
#include "stdc++.h"
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define rep2(i, s, n) for (int i = s; i < (int)(n); i++)
#define chmax(a, b) a = max(a, b)
#define chmin(a, b) a = max(a, b)
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()

using namespace std;
using ll = long long;
using pii = pair<int, int>;

void	solve()
{
	int h, w;
	cin >> h >> w;
	vector<string> v(h);
	rep(i, h) cin >> v[i];
	rep(i, h) {
		cout << v[i] << endl;
		cout << v[i] << endl;
	}
}

int		main(void)
{
	ios::sync_with_stdio(0);
	cin.tie(0);
	
	solve();
}

Compiler output:
a.cc:2:10: fatal error: stdc++.h: No such file or directory
    2 | #include "stdc++.h"
      |          ^~~~~~~~~~
compilation terminated.
Language: C++

9 20
.....***....***.....
....*...*..*...*....
...*.....**.....*...
...*.....*......*...
....*.....*....*....
.....**..*...**.....
.......*..*.*.......
........**.*........
.........**.........

Compiler output:
a.cc:1:1: error: expected unqualified-id before numeric constant
    1 | 9 20
      | ^
Language: C

9 20
.....***....***.....
....*...*..*...*....
...*.....**.....*...
...*.....*......*...
....*.....*....*....
.....**..*...**.....
.......*..*.*.......
........**.*........
.........**.........

Compiler output:
main.c:1:1: error: expected identifier or '(' before numeric constant
    1 | 9 20
      | ^
Language: C++

h,w=map(int,input().split())
lst=[list(input()) for _ in range(h)]
lst_1=[]
for i in lst:
    print(*i)
    print(*i)

Compiler output:
a.cc:1:1: error: 'h' does not name a type
    1 | h,w=map(int,input().split())
      | ^
Language: C++

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

int main(){
    char arr[200][200];
    int h,w;
    cin>>h>>w;
    for(int i=0;i<h;i++){
        for(int j=0;j<w;j++){
            cin>>arr[i][j];
        }
    }
    for(int i=0;i<h;i++){
        for(int j=0;j<w;j++){
            cout<<arr[i][j]<<" ";
        }
        cout<<"\n";
        for(int k=0;k<w;k++){
            cout<<arr[i][k]<<" ";
        }

        cout<<"\n";
    }
    cout<<"\n"
    return 0;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:24:15: error: expected ';' before 'return'
   24 |     cout<<"\n"
      |               ^
      |               ;
   25 |     return 0;
      |     ~~~~~~
Language: C++

using namespace std;
int main()
{
    int h,w;
    cin>>h>>w;
    char c[100][100];
    for(int i=0;i<h;i++)
    {
        for(int j=0;j<w;j++)
        {
            cin>>c[i][j];
        }
    }
    for(int i=0;i<h;i++)
    {
        for(int k=0;k<2;k++)
        {
            for(int j=0;j<w;j++)
            {
            cout<<c[i][j];
            }
             cout<<endl;
        }
    }
    return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:5:5: error: 'cin' was not declared in this scope
    5 |     cin>>h>>w;
      |     ^~~
a.cc:1:1: note: 'std::cin' is defined in header '<iostream>'; this is probably fixable by adding '#include <iostream>'
  +++ |+#include <iostream>
    1 | using namespace std;
a.cc:20:13: error: 'cout' was not declared in this scope
   20 |             cout<<c[i][j];
      |             ^~~~
a.cc:20:13: note: 'std::cout' is defined in header '<iostream>'; this is probably fixable by adding '#include <iostream>'
a.cc:22:14: error: 'cout' was not declared in this scope
   22 |              cout<<endl;
      |              ^~~~
a.cc:22:14: note: 'std::cout' is defined in header '<iostream>'; this is probably fixable by adding '#include <iostream>'
a.cc:22:20: error: 'endl' was not declared in this scope
   22 |              cout<<endl;
      |                    ^~~~
a.cc:1:1: note: 'std::endl' is defined in header '<ostream>'; this is probably fixable by adding '#include <ostream>'
  +++ |+#include <ostream>
    1 | using namespace std;
Language: C++

C:\Users\yuki\CLionProjects\untitled\cmake-build-debug\untitled.exe
9 20
.....***....***.....
....*...*..*...*....
...*.....**.....*...
...*.....*......*...
....*.....*....*....
.....**..*...**.....
.......*..*.*.......
........**.*........
.........**..............***....***.....
.....***....***.....
....*...*..*...*....
....*...*..*...*....
...*.....**.....*...
...*.....**.....*...
...*.....*......*...
...*.....*......*...
....*.....*....*....
....*.....*....*....
.....**..*...**.....
.....**..*...**.....
.......*..*.*.......
.......*..*.*.......
........**.*........
........**.*........

.........**.........
.........**.........

Process finished with exit code 0


Compiler output:
a.cc:1:3: error: stray '\' in program
    1 | C:\Users\yuki\CLionProjects\untitled\cmake-build-debug\untitled.exe
      |   ^
a.cc:1:9: error: stray '\' in program
    1 | C:\Users\yuki\CLionProjects\untitled\cmake-build-debug\untitled.exe
      |         ^
a.cc:1:14: error: stray '\' in program
    1 | C:\Users\yuki\CLionProjects\untitled\cmake-build-debug\untitled.exe
      |              ^
a.cc:1:28: error: stray '\' in program
    1 | C:\Users\yuki\CLionProjects\untitled\cmake-build-debug\untitled.exe
      |                            ^
a.cc:1:37: error: stray '\' in program
    1 | C:\Users\yuki\CLionProjects\untitled\cmake-build-debug\untitled.exe
      |                                     ^
a.cc:1:55: error: stray '\' in program
    1 | C:\Users\yuki\CLionProjects\untitled\cmake-build-debug\untitled.exe
      |                                                       ^
a.cc:1:2: error: found ':' in nested-name-specifier, expected '::'
    1 | C:\Users\yuki\CLionProjects\untitled\cmake-build-debug\untitled.exe
      |  ^
      |  ::
a.cc:1:1: error: 'C' does not name a type
    1 | C:\Users\yuki\CLionProjects\untitled\cmake-build-debug\untitled.exe
      | ^
Language: C++

using namespace std;
int main()
{
    int h,w;
    cin>>h>>w;
    char c[100][100];
    for(int i=0;i<h;i++)
    {
        for(int j=0;j<w;j++)
        {
            cin>>c[i][j];
        }
    }
    for(int i=0;i<h;i++)
    {
        for(int k=0;k<2;k++)
        {
            for(int j=0;j<w;j++)
            {
            cout<<c[i][j];
            }
             cout<<endl;
        }
    }
    return 0;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:5:5: error: 'cin' was not declared in this scope
    5 |     cin>>h>>w;
      |     ^~~
a.cc:1:1: note: 'std::cin' is defined in header '<iostream>'; this is probably fixable by adding '#include <iostream>'
  +++ |+#include <iostream>
    1 | using namespace std;
a.cc:20:13: error: 'cout' was not declared in this scope
   20 |             cout<<c[i][j];
      |             ^~~~
a.cc:20:13: note: 'std::cout' is defined in header '<iostream>'; this is probably fixable by adding '#include <iostream>'
a.cc:22:14: error: 'cout' was not declared in this scope
   22 |              cout<<endl;
      |              ^~~~
a.cc:22:14: note: 'std::cout' is defined in header '<iostream>'; this is probably fixable by adding '#include <iostream>'
a.cc:22:20: error: 'endl' was not declared in this scope
   22 |              cout<<endl;
      |                    ^~~~
a.cc:1:1: note: 'std::endl' is defined in header '<ostream>'; this is probably fixable by adding '#include <ostream>'
  +++ |+#include <ostream>
    1 | using namespace std;
Language: C++

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

int main() {
    int h,w;
    cin >> h >> w;
    char c[w][h];
    char d[w*2][h];
    for(int i=0;i<w;i++){
        for(int j=0;j<h;j++){
            cin >> c[i][j];
            d[2*i][j]=s[i][j];
            d[2*i+1][j]=s[i][j];
        }
    }
    for(int i=0;i<2*w;i++){
        for(int j=0;j<h;j++){
            cout << d[i][j];
            if(j==h-1){
                cout << endl;
            }
        }
    }
}

Compiler output:
a.cc: In function 'int main()':
a.cc:12:23: error: 's' was not declared in this scope
   12 |             d[2*i][j]=s[i][j];
      |                       ^
Language: C++

#include <iostream>
using namespace std;
int H, W;
char C[101][101];
int main()
{
   
    cin >> H >> W;
    for (int i = 1; i <= H; i++) 
    {
        for (int j = 1; j <= W; j++)
        {
            cin >> C[i][j];
        }
    }
    for (int i = 1; i <= 2 * H; i++)
    {
        for (int j = 1; j <= W; j++)
        {
            int m = ceil((i + 1) / 2);
            cout << C[m][j];
        }
        cout << endl;
    }
     return 0;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:20:21: error: 'ceil' was not declared in this scope
   20 |             int m = ceil((i + 1) / 2);
      |                     ^~~~
Language: C++

#include<iostream>
#include<string>
using namespace std;
int main(){
  int h,w,i;
  cin >> h >> w;
  string c;
  for (i=0,i<h,i++) {
    cin >> c;
    cout << c << endl;
    cout << c << endl;
  }
  return 0;
}
  
  


Compiler output:
a.cc: In function 'int main()':
a.cc:8:19: error: expected ';' before ')' token
    8 |   for (i=0,i<h,i++) {
      |                   ^
      |                   ;
a.cc:13:3: error: expected primary-expression before 'return'
   13 |   return 0;
      |   ^~~~~~
a.cc:12:4: error: expected ';' before 'return'
   12 |   }
      |    ^
      |    ;
   13 |   return 0;
      |   ~~~~~~
a.cc:13:3: error: expected primary-expression before 'return'
   13 |   return 0;
      |   ^~~~~~
a.cc:12:4: error: expected ')' before 'return'
   12 |   }
      |    ^
      |    )
   13 |   return 0;
      |   ~~~~~~
a.cc:8:7: note: to match this '('
    8 |   for (i=0,i<h,i++) {
      |       ^
Language: C++

#include<iostream>
#include<string>
using nammespace std;
int main(){
  int h,w,i;
  cin >> h >> w;
  string c;
  for (i=0,i<h,i++) {
    cin >> c;
    cout << c << endl;
    cout << c << endl;
  }
  return 0;
}
  
  

Compiler output:
a.cc:3:7: error: expected nested-name-specifier before 'nammespace'
    3 | using nammespace std;
      |       ^~~~~~~~~~
a.cc: In function 'int main()':
a.cc:6:3: error: 'cin' was not declared in this scope; did you mean 'std::cin'?
    6 |   cin >> h >> w;
      |   ^~~
      |   std::cin
In file included 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:7:3: error: 'string' was not declared in this scope
    7 |   string c;
      |   ^~~~~~
a.cc:7:3: 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:
/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:8:19: error: expected ';' before ')' token
    8 |   for (i=0,i<h,i++) {
      |                   ^
      |                   ;
a.cc:13:3: error: expected primary-expression before 'return'
   13 |   return 0;
      |   ^~~~~~
a.cc:12:4: error: expected ';' before 'return'
   12 |   }
      |    ^
      |    ;
   13 |   return 0;
      |   ~~~~~~
a.cc:13:3: error: expected primary-expression before 'return'
   13 |   return 0;
      |   ^~~~~~
a.cc:12:4: error: expected ')' before 'return'
   12 |   }
      |    ^
      |    )
   13 |   return 0;
      |   ~~~~~~
a.cc:8:7: note: to match this '('
    8 |   for (i=0,i<h,i++) {
      |       ^
Language: C++

#include <bits/stdc++.h>
using namespace std;
int main()
{
	long long a,b;
	char s[101];
	cin >> a >> b;
	for (int i = 1; i <= b; i++)
		{
			cin >> s;
			put(s);
			put(s);
		}
	return 0;	
 } 

Compiler output:
a.cc: In function 'int main()':
a.cc:11:25: error: 'put' was not declared in this scope; did you mean 'putw'?
   11 |                         put(s);
      |                         ^~~
      |                         putw
Language: C++

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

int main(){
  int h,w;
  cin >> h >> w;
  char buf[101];
  for(int i=0;i<h;i++){
    cin >> buf;
    cout << buf << endl;
    cout << buf << endl;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:12:2: error: expected '}' at end of input
   12 | }
      |  ^
a.cc:4:11: note: to match this '{'
    4 | int main(){
      |           ^
Language: C++

#include <bits/stdc++.h>
#include <math.h>
#define rep(i, n) for(int64_t i = 0; i < n; ++i)
using namespace std;

int main() {
  int h, w;
  cin >> h >> w;
  vector<string> v(n);
  rep(i, h) cin >> v[i];
  rep(i, h) cout << v[i] << endl <<  v[i] << endl;
  return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:9:20: error: 'n' was not declared in this scope
    9 |   vector<string> v(n);
      |                    ^
Language: C++

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

int main(){
  int H,W;
  cin>>H>>W;
  for(int i=0;i<H;i++){
    string s;
    cin>>s;
    cout<<s<<endl;
    cout<<s<<endll;
  }
}

Compiler output:
a.cc: In function 'int main()':
a.cc:11:14: error: 'endll' was not declared in this scope
   11 |     cout<<s<<endll;
      |              ^~~~~
Language: C++

#include <iostream>
#include <cstdio>
#include <cstring>
#include <vector>
#include <algorithm>
using namespace std;
int h, w;
vector<string> mat;
int main() {
  cin>>h>>w;
  mat.clear();
  mat2.clear();
  for (int i = 0; i < h; ++i) {
  	string s;
    cin>>s;
    mat.push_back(s);
  }
  for (int i = 1; i <= 2 * h; ++i) {
    cout<<mat[(i+1)/2-1]<<endl;
  }
	return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:12:3: error: 'mat2' was not declared in this scope; did you mean 'mat'?
   12 |   mat2.clear();
      |   ^~~~
      |   mat
Language: Java

import java.util.*;
public class Main{
 public static void main(String[] args){
   Scanner sc = new Scanner(System.in);
 
   int H = sc.nextInt();
   int W = sc.nextInt();
   char[][] ccc = new char[H][W];
   for(int i =0;i<N;i++)
   {
     ccc[i] = sc.next().toCharArray();
   }
   for(int i=0;i<N;i++)
   {
     System.out.println(ccc[i].toString());
     System.out.println(ccc[i].toString());
   }
 }
}

Compiler output:
Main.java:9: error: cannot find symbol
   for(int i =0;i<N;i++)
                  ^
  symbol:   variable N
  location: class Main
Main.java:13: error: cannot find symbol
   for(int i=0;i<N;i++)
                 ^
  symbol:   variable N
  location: class Main
2 errors
Language: Java

import java.util.*;
public class Main{
 public static void main(String[] args){
   Scanner sc = new Scanner(System.in);
 
   int H = sc.nextInt();
   int W = sc.nextInt();
   char[][] ccc = new char[H][W];
   for(int i =0;i<N;i++)
   {
     char[i] = sc.next().toCharArray();
   }
   for(int i=0;i<N;i++)
   {
     System.out.println(char[i].toString());
     System.out.println(char[i].toString());
   }
 }
}

Compiler output:
Main.java:11: error: ']' expected
     char[i] = sc.next().toCharArray();
          ^
Main.java:11: error: ';' expected
     char[i] = sc.next().toCharArray();
           ^
Main.java:15: error: ']' expected
     System.out.println(char[i].toString());
                             ^
Main.java:15: error: ';' expected
     System.out.println(char[i].toString());
                              ^
Main.java:15: error: ';' expected
     System.out.println(char[i].toString());
                                          ^
Main.java:16: error: ']' expected
     System.out.println(char[i].toString());
                             ^
Main.java:16: error: ';' expected
     System.out.println(char[i].toString());
                              ^
Main.java:16: error: ';' expected
     System.out.println(char[i].toString());
                                          ^
8 errors
Language: C

#include<stdio.h>
#include<stdlib.h>
struct n{
  char s[101];
}
int main(){
  int a,b;
  scanf("%d %d",&a,&b);
  struct n c[a];
  for(int i=0; i<a; i++){
    scanf("%s",c[i].s);
  }
  for(int i=0; i<a; i++){
    printf("%s\n%s\n",c[i].s,c[i].s);
  }
  return 0;}

Compiler output:
main.c:6:1: error: expected ';', identifier or '(' before 'int'
    6 | int main(){
      | ^~~
Language: C++

#include <iostream>
#include <cstring>
#define MOD 1000000007
using namespace std;

int n;

int main(void){
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	cin>>h>>w;
	for (int i = 0; i < h; ++i){
		string arr='';
		cin>>arr;
		cout<<arr<<endl<<arr<<endl;
	}
	
	return 0;
}

Compiler output:
a.cc:14:28: error: empty character constant
   14 |                 string arr='';
      |                            ^~
a.cc: In function 'int main()':
a.cc:12:14: error: 'h' was not declared in this scope
   12 |         cin>>h>>w;
      |              ^
a.cc:12:17: error: 'w' was not declared in this scope
   12 |         cin>>h>>w;
      |                 ^
a.cc:14:28: error: conversion from 'char' to non-scalar type 'std::string' {aka 'std::__cxx11::basic_string<char>'} requested
   14 |                 string arr='';
      |                            ^~
Language: C++

#include<bits/stdc++.h>
using namespace std;
int main()
{
	int h,w;
	cin>>h>>w;
	string s[1000];
	for(int i=1;i<=h;i++){
		cin>>s[i];
	}
	for(int j=1;j<=h;j++){
		cout<<s[i]<<endl<<s[i]<<endl;
	}
	return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:12:25: error: 'i' was not declared in this scope
   12 |                 cout<<s[i]<<endl<<s[i]<<endl;
      |                         ^
Language: C++

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

int main(){
  int h,w;
  cin >> h >> w;
  for(int i=0;i<h,i++){
    string a;
    cin >> a;
    cout << a << endl;
    cout << a << endl;
  }
}

Compiler output:
a.cc: In function 'int main()':
a.cc:7:22: error: expected ';' before ')' token
    7 |   for(int i=0;i<h,i++){
      |                      ^
      |                      ;
Language: Java

import java.util.*;

class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int H = sc.nextInt();
    int W = sc.nextInt();
    String pix[][] = new String[H][W];
    for(int i = 0;i < H;i++){
      for(int j = 0;j < W;j++){
        pix[i][j] = sc.next();
      }
    }

    for(int k = 0;k < H;k++){
      for(int l = 0;l < W;l++){
        if(l != W -1){
          System.out.print(pix[k][l]);
        }else{
          System.out.println(pix[k][l]);
        }
      }
      for(int m = 0;m < W;m++){
        if(m != W -1){
          System.out.print(pix[k][l]);
        }else{
          System.out.println(pix[k][l]);
        }
      }
    }


  }
}


Compiler output:
Main.java:25: error: cannot find symbol
          System.out.print(pix[k][l]);
                                  ^
  symbol:   variable l
  location: class Main
Main.java:27: error: cannot find symbol
          System.out.println(pix[k][l]);
                                    ^
  symbol:   variable l
  location: class Main
2 errors
Language: Java

import java.util.*;

class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int H = sc.nextInt();
    int W = sc.nextInt();
    String pix[][] = new String[H][W];
    for(int i = 0;i < H;i++){
      for(int j = 0;j < W;j++){
        pix[i][j] = sc.next();
      }
    }

    for(int k = 0;k < H;k++){
      for(int l = 0;l < W;l++){
        if(l != W -1){
          System.out.print(pix[k][l]);
        }else{
          System.out.println(pix[k][l]);
        }
      }
      for(int m = 0;m < W;m++){
        if(l != W -1){
          System.out.print(pix[k][l]);
        }else{
          System.out.println(pix[k][l]);
        }
      }
    }


  }
}


Compiler output:
Main.java:24: error: cannot find symbol
        if(l != W -1){
           ^
  symbol:   variable l
  location: class Main
Main.java:25: error: cannot find symbol
          System.out.print(pix[k][l]);
                                  ^
  symbol:   variable l
  location: class Main
Main.java:27: error: cannot find symbol
          System.out.println(pix[k][l]);
                                    ^
  symbol:   variable l
  location: class Main
3 errors
Language: C++

#include <iostream>
#include <algorithm>
#include <vector>
#include <cmath>
#include <string>
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
const int mod = 1000000007;

int main() {
    ios::sync_with_stdio(false);
    int n, m;
    string s;
    cin >> n >> m;
    while (n--) cin >> s, cout << s << '\n' << s << '\n'
}


Compiler output:
a.cc: In function 'int main()':
a.cc:16:57: error: expected ';' before '}' token
   16 |     while (n--) cin >> s, cout << s << '\n' << s << '\n'
      |                                                         ^
      |                                                         ;
   17 | }
      | ~
Language: C++

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

int main() {
  int h,w;
  cin >> h >> w;
  vector<vector<char>> a(h,vector<char>(w));
  for(int i=0;i<h;i++){
    for(int j=0;j<w;j++){
      cin >> a.at(h).at(w);
    }
  }
  for(int i=0;i<2*h;i++){
    for(int j=0;i<w;j++){
        cout << a.at(i/2).at(j);
    }
    cout << << endl;
  }
  cout <<  << endl;
  
  return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:17:13: error: expected primary-expression before '<<' token
   17 |     cout << << endl;
      |             ^~
a.cc:19:12: error: expected primary-expression before '<<' token
   19 |   cout <<  << endl;
      |            ^~
Language: C++

H,W = map(int,input().split())
listA =[]
while True:
    try:
        listA.append(list(map(str,input().split())))
    except:
        break;
for i in range(0,2*H):
    for j in range(0,W):
        if j == W-1:
            print(listA[i//2][0][j])
        else:
            print(listA[i//2][0][j],end="")

Compiler output:
a.cc:1:1: error: 'H' does not name a type
    1 | H,W = map(int,input().split())
      | ^
a.cc:8:1: error: expected unqualified-id before 'for'
    8 | for i in range(0,2*H):
      | ^~~
Language: C++

#include<iostream>
#include<cstdio>
#include<cmath>
#include<string>
#include<cstring>
#include<algorithm>
using namespace std;
string gay;
int n,m;
int main()
{
	cin<>>n>>m;
	for(int i=1; i<=n; i++)
	{
	    cin>>gay;
	    cout<<gay<<gay;
	}
	return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:12:13: error: expected primary-expression before '>>' token
   12 |         cin<>>n>>m;
      |             ^~
Language: C++

#include<iostream>
#include<cstdio>
#include<cmath>
#include<string>
#include<cstring>
#include<algorithm>
using namespace std;
string gay;
int n,m;
int main()
{
	cin<>>n>>m;
	for(int i=1; i<=n; i++)
	{
	    cin>>gay;
	    cout<<gay<<emdl<<gay<<endl;
	}
	return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:12:13: error: expected primary-expression before '>>' token
   12 |         cin<>>n>>m;
      |             ^~
a.cc:16:24: error: 'emdl' was not declared in this scope
   16 |             cout<<gay<<emdl<<gay<<endl;
      |                        ^~~~
Language: C++

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

int main() {
  int h, w;
  cin >> h >> w;
  vector<string> org(h);
  rep(i, h) {
    cin >> org[i];
  }
  rep(i, h) {
    cout << org[i] << endl;
    cout << org[i] << endl;
  }
  return 0;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:8:7: error: 'i' was not declared in this scope
    8 |   rep(i, h) {
      |       ^
a.cc:8:3: error: 'rep' was not declared in this scope
    8 |   rep(i, h) {
      |   ^~~
Language: C++

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

int main(){
 int  a, b;
  cin >> a >> b ;
  
  string s[a];
  
  for(int i =0;i<a;i++)
    cin >> s[i] ;
  
   
 for(int i =0;i<a;i++)
  
      cout <<s[i]<<endl;
      cout <<s[i]<<endl ;
  
  
}


Compiler output:
a.cc: In function 'int main()':
a.cc:17:16: error: 'i' was not declared in this scope
   17 |       cout <<s[i]<<endl ;
      |                ^
Language: C++

#include<bits/stdc++.h>
using namespace std;
int n, m;
string s;
int main(void){
    cin>>n>>m;
    for(int i=1;i<=n;i++){
        cin>>a;
        cout<<a<<"\n"<<a<<endl;
    }
} 

Compiler output:
a.cc: In function 'int main()':
a.cc:8:14: error: 'a' was not declared in this scope
    8 |         cin>>a;
      |              ^
Language: C

#include<stdio.h>
int main(){
  int h,w;
  char a[h][w];
  scanf("%d %d",&h,&w);
  for(int i=0;i<h;i++){
    for(int o=0;o<w;o++){
      scanf("%c",&a[i][o]);
    }
  }
  for(int i=0;i<h;i++){
    for(int o=0;o<w;o++){
      printf("%c",a[i][o]);
    }
    ptintf("\n");
    for(int o=0;o<w;o++){
      printf("%c",a[i][o]);
    }
    printf("\n");
  }
}


Compiler output:
main.c: In function 'main':
main.c:15:5: error: implicit declaration of function 'ptintf'; did you mean 'printf'? [-Wimplicit-function-declaration]
   15 |     ptintf("\n");
      |     ^~~~~~
      |     printf
Language: C

#include<stdio.h>
int main(){
  int h,w;
  char a[h][w];
  scanf("%d %d",&h,&w);
  for(int i=0;i<h;i++){
    for(int o=0;o<w;o++){
      scanf("%c",a[i][o]);
    }
  }
  for(int i=0;i<h;i++){
    for(int o=0;o<w;o++){
      printf("%c",&a[i][o]);
    }
    ptintf("\n");
    for(int o=0;o<w;o++){
      printf("%c",&a[i][o]);
    }
    printf("\n");
  }
}


Compiler output:
main.c: In function 'main':
main.c:15:5: error: implicit declaration of function 'ptintf'; did you mean 'printf'? [-Wimplicit-function-declaration]
   15 |     ptintf("\n");
      |     ^~~~~~
      |     printf
Language: C

#include<stdio.h>
int main(){
  int h,w;
  char a[h][w]
  scanf("%d %d",&h,&w);
  for(int i=0;i<h;i++){
    for(int o=0;o<w;o++){
      scanf("%c",a[i][o]);
    }
  }
  for(int i=0;i<h;i++){
    for(int o=0;o<w;o++){
      printf("%c",&a[i][o]);
    }
    ptintf("\n");
    for(int o=0;o<w;o++){
      printf("%c",&a[i][o]);
    }
    printf("\n");
  }
}


Compiler output:
main.c: In function 'main':
main.c:5:3: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'scanf'
    5 |   scanf("%d %d",&h,&w);
      |   ^~~~~
main.c:8:18: error: 'a' undeclared (first use in this function)
    8 |       scanf("%c",a[i][o]);
      |                  ^
main.c:8:18: note: each undeclared identifier is reported only once for each function it appears in
main.c:15:5: error: implicit declaration of function 'ptintf'; did you mean 'printf'? [-Wimplicit-function-declaration]
   15 |     ptintf("\n");
      |     ^~~~~~
      |     printf
Language: C

#inlcude<stdio.h>
int main(){
  int h,w;
  char a[h][w]
  scanf("%d %d",&h,&w);
  for(int i=0;i<h;i++){
    for(int o=0;o<w;o++){
      scanf("%c",a[i][o]);
    }
  }
  for(int i=0;i<h;i++){
    for(int o=0;o<w;o++){
      printf("%c",&a[i][o]);
    }
    ptintf("\n");
    for(int o=0;o<w;o++){
      printf("%c",&a[i][o]);
    }
    printf("\n");
  }
}


Compiler output:
main.c:1:2: error: invalid preprocessing directive #inlcude; did you mean #include?
    1 | #inlcude<stdio.h>
      |  ^~~~~~~
      |  include
main.c: In function 'main':
main.c:5:3: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'scanf'
    5 |   scanf("%d %d",&h,&w);
      |   ^~~~~
main.c:5:3: error: implicit declaration of function 'scanf' [-Wimplicit-function-declaration]
main.c:1:1: note: include '<stdio.h>' or provide a declaration of 'scanf'
  +++ |+#include <stdio.h>
    1 | #inlcude<stdio.h>
main.c:5:3: warning: incompatible implicit declaration of built-in function 'scanf' [-Wbuiltin-declaration-mismatch]
    5 |   scanf("%d %d",&h,&w);
      |   ^~~~~
main.c:5:3: note: include '<stdio.h>' or provide a declaration of 'scanf'
main.c:8:18: error: 'a' undeclared (first use in this function)
    8 |       scanf("%c",a[i][o]);
      |                  ^
main.c:8:18: note: each undeclared identifier is reported only once for each function it appears in
main.c:13:7: error: implicit declaration of function 'printf' [-Wimplicit-function-declaration]
   13 |       printf("%c",&a[i][o]);
      |       ^~~~~~
main.c:13:7: note: include '<stdio.h>' or provide a declaration of 'printf'
main.c:13:7: warning: incompatible implicit declaration of built-in function 'printf' [-Wbuiltin-declaration-mismatch]
main.c:13:7: note: include '<stdio.h>' or provide a declaration of 'printf'
main.c:15:5: error: implicit declaration of function 'ptintf' [-Wimplicit-function-declaration]
   15 |     ptintf("\n");
      |     ^~~~~~
main.c:17:7: warning: incompatible implicit declaration of built-in function 'printf' [-Wbuiltin-declaration-mismatch]
   17 |       printf("%c",&a[i][o]);
      |       ^~~~~~
main.c:17:7: note: include '<stdio.h>' or provide a declaration of 'printf'
main.c:19:5: warning: incompatible implicit declaration of built-in function 'printf' [-Wbuiltin-declaration-mismatch]
   19 |     printf("\n");
      |     ^~~~~~
main.c:19:5: note: include '<stdio.h>' or provide a declaration of 'printf'
Language: C

#inlcude<stdio.h>
int main(){
  int h,w;
  char a[h][w]
  scanf("%d%d",&h,&w);
  for(int i=0;i<h;i++){
    for(int o=0;o<w;o++){
      scanf("%c",a[i][o]);
    }
  }
  for(int i=0;i<h;i++){
    for(int o=0;o<w;o++){
      printf("%c",&a[i][o]);
    }
    ptintf("\n");
    for(int o=0;o<w;o++){
      printf("%c",&a[i][o]);
    }
    printf("\n");
  }
}


Compiler output:
main.c:1:2: error: invalid preprocessing directive #inlcude; did you mean #include?
    1 | #inlcude<stdio.h>
      |  ^~~~~~~
      |  include
main.c: In function 'main':
main.c:5:3: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'scanf'
    5 |   scanf("%d%d",&h,&w);
      |   ^~~~~
main.c:5:3: error: implicit declaration of function 'scanf' [-Wimplicit-function-declaration]
main.c:1:1: note: include '<stdio.h>' or provide a declaration of 'scanf'
  +++ |+#include <stdio.h>
    1 | #inlcude<stdio.h>
main.c:5:3: warning: incompatible implicit declaration of built-in function 'scanf' [-Wbuiltin-declaration-mismatch]
    5 |   scanf("%d%d",&h,&w);
      |   ^~~~~
main.c:5:3: note: include '<stdio.h>' or provide a declaration of 'scanf'
main.c:8:18: error: 'a' undeclared (first use in this function)
    8 |       scanf("%c",a[i][o]);
      |                  ^
main.c:8:18: note: each undeclared identifier is reported only once for each function it appears in
main.c:13:7: error: implicit declaration of function 'printf' [-Wimplicit-function-declaration]
   13 |       printf("%c",&a[i][o]);
      |       ^~~~~~
main.c:13:7: note: include '<stdio.h>' or provide a declaration of 'printf'
main.c:13:7: warning: incompatible implicit declaration of built-in function 'printf' [-Wbuiltin-declaration-mismatch]
main.c:13:7: note: include '<stdio.h>' or provide a declaration of 'printf'
main.c:15:5: error: implicit declaration of function 'ptintf' [-Wimplicit-function-declaration]
   15 |     ptintf("\n");
      |     ^~~~~~
main.c:17:7: warning: incompatible implicit declaration of built-in function 'printf' [-Wbuiltin-declaration-mismatch]
   17 |       printf("%c",&a[i][o]);
      |       ^~~~~~
main.c:17:7: note: include '<stdio.h>' or provide a declaration of 'printf'
main.c:19:5: warning: incompatible implicit declaration of built-in function 'printf' [-Wbuiltin-declaration-mismatch]
   19 |     printf("\n");
      |     ^~~~~~
main.c:19:5: note: include '<stdio.h>' or provide a declaration of 'printf'
Language: C++

// --------------------<optimizations>--------------------
#pragma GCC optimize("O3")
//(UNCOMMENT WHEN HAVING LOTS OF RECURSIONS)\
#pragma comment(linker, "/stack:200000000")
//(UNCOMMENT WHEN TRYING TO BRUTEFORCE WITH A LOT OF LOOPS)\
#pragma GCC optimize("unroll-loops")
#include<bits/stdc++.h>

using namespace std;

#define ll long long
#define mp make_pair
#define pb push_back
#define eb emplace_back
#define pii pair<ll,ll>
#define vpii vector<pair<ll,ll> >
#define F first
#define S second
#define ld long double
#define built __builtin_popcountll
#define mst(a,i) memset(a,i,sizeof(a))
#define all(x) x.begin(),x.end()
#define itit(it,a) for(auto it=(a).begin(); it!=(a).end(); it++)
#define rep(i,a,b) for(ll i=a; i<b; i++)
#define repr(i,a,b) for(ll i=a; i>b; i--)
#define reprr(i,a,b) for(ll i=a; i>=b; i--)
#define pi 3.14159265358979323846264338327950288419716939937510582097494459230
ll max3(ll x,ll y,ll z) {return max(max(x,y),z);}
ll min3(ll x,ll y,ll z) {return min(min(x,y),z);}
const ll M=2e5+10,M2=1e6+10,mod=1e9+7,inf=1e17+10;
void add(int& a, int b) {a+=b;if(a>=mod){a-=mod;}}
#define trace1(x)			 	 cerr<<#x<<": "<<x<<endl
#define trace2(x, y)		 	 cerr<<#x<<": "<<x<<" | "<<#y<<": "<<y<<endl
#define trace3(x, y, z)		 	 cerr<<#x<<":" <<x<<" | "<<#y<<": "<<y<<" | "<<#z<<": "<<z<<endl
#define trace4(a, b, c, d)	 	 cerr<<#a<<": "<<a<<" | "<<#b<<": "<<b<<" | "<<#c<<": "<<c<<" | "<<#d<<": "<<d<<endl
#define trace5(a, b, c, d, e)	 cerr<<#a<<": "<<a<<" | "<<#b<<": "<<b<<" | "<<#c<<": "<<c<<" | "<<#d<<": "<<d<<" | "<<#e<< ": "<<e<<endl
#define trace6(a, b, c, d, e, f) cerr<<#a<<": "<<a<<" | "<<#b<<": "<<b<<" | "<<#c<<": "<<c<<" | "<<#d<<": "<<d<<" | "<<#e<< ": "<<e<<" | "<<#f<<": "<<f<<endl
int X[] = {0, 1, 0, -1};
int Y[] = {-1, 0, 1, 0};
ll power(ll x,ll n){ll result=1;while(n>0){if(n%2==1)result=(result*x)%mod; x=((x%mod)*(x%mod))%mod;n=n/2;}return result;}


int main()
{
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	ll h,w;
	cin >> h >> w;
	vector<string> s(h);
	rep(i,0,h) cin >> s[i];

	for(i=0; i<h; i++){
		cout << s[i] << "\n";
		cout << s[i] << "\n";
	}
	return 0;
}
/* The judge is never wrong! Your code is buggy
   Look for:
 * * Read the problem carefully.
 * * Don't forget to sort(), mod, ll!!!!
 * * Initial value = +/- infinity instead of zero!!!
 * * an easier and alternate approach
 * * read the problem statement carefully
 * * if concept is correct and still WA, try with a different implementation
 * * special cases (n=1?)
 * * if you have no idea just guess the appropriate well-known algorithm instead of doing nothing :/
 */


Compiler output:
a.cc: In function 'int main()':
a.cc:53:13: error: 'i' was not declared in this scope
   53 |         for(i=0; i<h; i++){
      |             ^
Language: C++

//ABC049
#include<bits/stdc++.h>
using namespace std;

int main(){
  int h,w;
  cin >> h >> w;
  vector<vector<int>> a(h,vector<int>(w));
  vector<vector<int>> ans(h*2,vector<int>(w));
  
  for(int i=0; i<h; i++){
    for(inr j=0; j<w; j++){
      cin >> a[h][w];
    }
  }
  for(int i=0; i<h; i++){
    for(inr j=0; j<w; j++){
      ans[i*2][j]= a[i][j];
      ans[i*2+1][j]= a[i][j]; 
    }
  }
  for(int i=0; i<h; i++){
    for(inr j=0; j<w; j++){
      cout << ans[i][j];
      
      if(w-i==1)  cout << endl;
      else  cout << " ";
    }
  }
}

Compiler output:
a.cc: In function 'int main()':
a.cc:12:9: error: 'inr' was not declared in this scope; did you mean 'int'?
   12 |     for(inr j=0; j<w; j++){
      |         ^~~
      |         int
a.cc:12:18: error: 'j' was not declared in this scope
   12 |     for(inr j=0; j<w; j++){
      |                  ^
a.cc:17:9: error: 'inr' was not declared in this scope; did you mean 'int'?
   17 |     for(inr j=0; j<w; j++){
      |         ^~~
      |         int
a.cc:17:18: error: 'j' was not declared in this scope
   17 |     for(inr j=0; j<w; j++){
      |                  ^
a.cc:23:9: error: 'inr' was not declared in this scope; did you mean 'int'?
   23 |     for(inr j=0; j<w; j++){
      |         ^~~
      |         int
a.cc:23:18: error: 'j' was not declared in this scope
   23 |     for(inr j=0; j<w; j++){
      |                  ^