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

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

const int INF = 1e9;
const int MOD = 1e9+7;
const ll LINF = 1e18;

#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n) for(int i=0;i<(n);++i)
#define REPR(i,n) for(int i=n;i>=0;i--)
#define ALL(v) (v.begin(),v.end())
#define COUT(x) cout<<(x)<<endl

int main() {
    int n;
    cin >> n;
    map<ll,int> mp;
    REP(i,n){
        ll t;
        cin >> t;
        mp[-t]++;
    }
    vector<ll> v;
    for(const auto& e:mp){
        ll a = e.first;
        int b = e.second;
        if(a>=2)v.push_back(b);
        if(a>=4){v.push_back(b);v.push_back(b)}
        if(v.size()>=2){
            COUT(v[0]*v[1]);
            return 0;
        }
    }
    COUT(0);
    return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:29:47: error: expected ';' before '}' token
   29 |         if(a>=4){v.push_back(b);v.push_back(b)}
      |                                               ^
      |                                               ;
Language: C++

#include <vector>
#include <string>
#include <iostream>
#include <queue>
#include <algorithm>
#include <functional>
#include <map>
#include <array>
#include <cmath>

using namespace std;

vector<int> poles;


int main(int argc, char* argv[]){
    int N;
    cin >> N;
    poles.resize(N, 0);

    for(int i = 0; i < N; ++i){
        cin >> poles.at(i);
    }

    std::sort(poles.begin(), poles.end(), greater<int>();


    long long area = 0;
    int count = 0;
    int prev = -1;

    for(int i = 0; i < poles.size(); ++i){
        if(poles[i] == prev){
            ++count;
            if(count == 1){
                area = prev;
            }
            else{
                area *= prev;
                cout << area;
                return 0;
            }
            prev = -1;
        }
        else{
            prev = poles[i];
        }
    }


    cout << 0;
}


Compiler output:
a.cc: In function 'int main(int, char**)':
a.cc:25:57: error: expected ')' before ';' token
   25 |     std::sort(poles.begin(), poles.end(), greater<int>();
      |              ~                                          ^
      |                                                         )
Language: C++

// -----------------------------------
// Author     : MatsuTaku
// Affiliation: Tokushima University
// Country    : Japan
// Date       : 04/07/2020
// -----------------------------------

#include <bits/stdc++.h>

using namespace std;
using ll = long long;

int main() {
  cin.tie(nullptr); ios::sync_with_stdio(false);

  map<ll, int> L;
  int n; cin>>n;
  for (int i = 0; i < n; i++) {
    int a; cin>>a;
    L[a]++;
  }
  auto solve = [&]() -> ll {
    ll a;
    auto it = --L.end();
    for (; it != L.end(); --it) {¥
      if (it->second <= 1)
        continue;
      if (it->second >= 4)
        return it->first*it->first;
      if (it->second >= 2) {
        a = it->first;
        break;
      }
    }
    for (--it; it != L.end(); --it) {
      if (it->second <= 1)
        continue;
      if (it->second >= 2) {
        return a*it->first;
      }
    }
    return 0;
  };
  cout << solve() << endl;

  return 0;
}


Compiler output:
a.cc:25:34: error: extended character ¥ is not valid in an identifier
   25 |     for (; it != L.end(); --it) {¥
      |                                  ^
a.cc: In lambda function:
a.cc:25:34: error: '\U000000a5' was not declared in this scope
   25 |     for (; it != L.end(); --it) {¥
      |                                  ^
Language: C++

N = int(input())
A = list(map(int,input().split()))
dls = []
A.sort()
A.reverse()
now = 0
for i in range(N-1):
  if now >= N-1:
    break
  else:
    if A[now] == A[now+1]:
      dls.append(A[now])
      now += 2
    else:
      now += 1
if len(dls) >= 2:
  print(dls[0]*dls[1])
else:
  print(0)

Compiler output:
a.cc:1:1: error: 'N' does not name a type
    1 | N = int(input())
      | ^
Language: C++

n = int(input())
a = list(map(int, input().split()))

a.sort()

tmp_val = 0
pair_val = 0
for i in range(n-1, -1, -1):
  if tmp_val == a[i]:
    if pair_val != 0:
      print(pair_val * a[i])
      exit()
    else:
      pair_val = a[i]
      tmp_val = 0
  else:
    tmp_val = a[i]

print(0)

Compiler output:
a.cc:1:1: error: 'n' does not name a type
    1 | n = int(input())
      | ^
Language: C++

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

int main() {
  int n;
  cin >> n;
  vector<int> a(n);
  for(int i = 0; i < n; i++){
    cin >> a.at(i);
  }
  sort(a.begin(), a.end());
  int len1 = 0;
  int len2 = 0;
  for(int i = 0; i < n - 1; i++){
    if(a.at(i) == a.at(i + 1)){
      if(flag == 0){
        if(a.at(i) != len1){
          len1 = a.at(i);
          flag++;
        }
      }else if(flag == 1){
        if(a.at(i) != len2){
          len2 = a.at(i);
          flag++;
          break;
        }
      }
    }
  }
  if(flag != 2){
    cout << 0;
  }else{
    cout << len1 * len2;
  }
}


Compiler output:
a.cc: In function 'int main()':
a.cc:16:10: error: 'flag' was not declared in this scope
   16 |       if(flag == 0){
      |          ^~~~
a.cc:30:6: error: 'flag' was not declared in this scope
   30 |   if(flag != 2){
      |      ^~~~
Language: C++

#include<stdio.h>
#include<vector>
#include<iostream> //c++
#include<algorithm>
/*
int main(){
	int a=0;
	char A[5];
	for (int i = 0; i < 5; i++) {
		scanf("%c\n", &A[i]);
	}
	
	for(int i = 0; i < 5; i++) {
		if (A[i] =='A' &&A[i + 1]=='C') {
			a = 1;
		
		}
	}
	if (a == 1) {
		printf("Yes");

	}
	else {
		printf("No");
	}
}*/

using namespace std;
/*int main() {
	int g;
	int  N,Num=0;
	vector<int>a;
	cin >> N;
	for (int i = 0; i < N;i++) {

		cin >> g;

		a.push_back(g);
	

	}
	int t,p=0;
	while (true) {
		t=a[p] ;
		a[p] = -1;
		p = t;
		if (p == -1) {
			Num = -1;
			break;
		}
			Num++;
			if (p == 2) {
				break;
			}
			p = p - 1;
	}
	cout << Num;
	

}*/

int main() {
	int N,g;
	vector<int>a;
	cin >> N;
	for (int i = 0; i< N; i++) {
		cin >> g;
		a.push_back(g);
	}
	sort(a.begin(), a.end());
	int Num1=0,Num2=0,Num;
	for (int i = 0; i < N; i++)
	{
		if (a[i] == a[i + 1] &&a[i]>= Num1) {
			Num2 = Num1;
			Num1 = a[i];
			i++;
		}
	
	Num = Num1 * Num2;
	cout << Num;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:82:2: error: expected '}' at end of input
   82 | }
      |  ^
a.cc:62:12: note: to match this '{'
   62 | int main() {
      |            ^
Language: C++

#include<stdio.h>
#include<vector>
#include<iostream> //c++
#include<algorithm>
/*
int main(){
	int a=0;
	char A[5];
	for (int i = 0; i < 5; i++) {
		scanf("%c\n", &A[i]);
	}
	
	for(int i = 0; i < 5; i++) {
		if (A[i] =='A' &&A[i + 1]=='C') {
			a = 1;
		
		}
	}
	if (a == 1) {
		printf("Yes");

	}
	else {
		printf("No");
	}
}*/

using namespace std;
/*int main() {
	int g;
	int  N,Num=0;
	vector<int>a;
	cin >> N;
	for (int i = 0; i < N;i++) {

		cin >> g;

		a.push_back(g);
	

	}
	int t,p=0;
	while (true) {
		t=a[p] ;
		a[p] = -1;
		p = t;
		if (p == -1) {
			Num = -1;
			break;
		}
			Num++;
			if (p == 2) {
				break;
			}
			p = p - 1;
	}
	cout << Num;
	

}*/

int main() {
	int N,g;
	vector<int>a;
	scanf_s("%d",&N);
	for (int i = 0; i< N; ++i) {
		cin >> g;
		a.push_back(g);
	}
	sort(a.begin(), a.end());
	int Num1=0,Num2=0,Num;
	for (int i = 0; i < N; i++)
	{
		if (a[i] == a[i + 1] >= Num2)
			Num1 = a[i];
			Num2 = Num1;
	}
	Num = Num1 * Num2;
	cout << Num;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:65:9: error: 'scanf_s' was not declared in this scope; did you mean 'scanf'?
   65 |         scanf_s("%d",&N);
      |         ^~~~~~~
      |         scanf
Language: C++

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

int main() {
  int64_t n;
  cin>>n;
  vector<int64_t> a(n);
  for(int i=0;i<n;i++){
    cin>>a.at(i);
  }
  int64_t S=0;
  sort(a.begin(),a.end());
  reverse(a.begin(),a.end());
  int count=0;
  int resetcount=0;
  int64_t x=0,y=0;
  for(int i=0;i<n-1;i++){
    if(a.at(i)==a.at(i+1)){
      if(count==0){
        count++;
        x=a.at(i);
        continue;
      }
      if(count==1&&reset>0){
        count++;
        y=a.at(i);
        continue;
      }
      if(count==2){
        break;
      }
    }
    else{
      resetcount++;
    }
  }
  S=x*y;
  cout<<S<<endl;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:24:20: error: 'reset' was not declared in this scope
   24 |       if(count==1&&reset>0){
      |                    ^~~~~
Language: C++

#include<iostream>
#include<string>
#include<cstdio>
#include<cstring>
#include<vector>
#include<cmath>
#include<algorithm>
#include<functional>
#include<iomanip>
#include<queue>
#include<ciso646>
#include<random>
#include<map>
#include<set>
#include<complex>
#include<bitset>
#include<stack>
#include<unordered_map>
#include<utility>
#include<cassert>
using namespace std;

typedef long long ll;
typedef unsigned long long ul;
typedef unsigned int ui;
typedef long double ld;
const ll mod = 1000000007;
const ll INF = mod * mod;
#define rep(i,n) for(int i=0;i<n;i++)
#define per(i,n) for(int i=n-1;i>=0;i--)
#define Rep(i,sta,n) for(int i=sta;i<n;i++)
#define rep1(i,n) for(int i=1;i<=n;i++)
#define per1(i,n) for(int i=n;i>=1;i--)
#define Rep1(i,sta,n) for(int i=sta;i<=n;i++)
typedef complex<ld> Point;
const ld eps = 1e-8;
const ld pi = acos(-1.0);
typedef pair<int, int> P;
typedef pair<ld, ld> LDP;
typedef pair<ll, ll> LP;
typedef vector<int> vec;
typedef vector<string> svec;
#define fr first
#define sc second
#define all(c) c.begin(),c.end()
#define pb push_back
//#define int long long

void solve() {
    int N; cin >> N;
    ll A[100100];
    rep(i, N) {
        cin >> A[i];
    }
    sort(A, A + N);
    reverse(A, A + N);
    ll now = A[N - 1], cnt = 0, ans = 1LL;
    per(i, N - 1) {
        if(now == A[i]) {
            ans *= now;
            cnt ++
            if(cnt == 2) break;
        } else {
            now = A[i];
        }
    }
    if(cnt <= 1) ans = 0;
    cout << ans << endl;
}

signed main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	//cout << fixed << setprecision(10);
	//init();
	solve();
	//cout << "finish" << endl;
    return 0;
}

Compiler output:
a.cc: In function 'void solve()':
a.cc:61:19: error: expected ';' before 'if'
   61 |             cnt ++
      |                   ^
      |                   ;
   62 |             if(cnt == 2) break;
      |             ~~
Language: C++

#include<bits/stdc++.h>
using namespace std;
#define int long long
#define fo(a,b) for(int a=0;a<b;a++)
#define Sort(a) sort(a.begin(),a.end())
#define rev(a) reverse(a.begin(),a.end())
 int wari(int a,int b) {
   if(a%b==0)
     return a/b;
   else
     return a/b+1;
 }
 int keta(int a){//桁数
  double b=a;
  b=log10(b);
  int c=b;
  return c+1;
 }
 int souwa(int a){
  return a*(a+1)/2;
 }
 int lcm(int a,int b){//最小公倍数
  int d=a,e=b,f;
  if(a<b)
    swap(a,b);
  int c,m=1;
  while(m){
    c=a%b;
    if(c==0){
       f=b;
      m--;
    }
    else{
      a=b;
      b=c;
 }
  }
  return d*e/f;
    }
  int gcm(int a,int b){//最大公約数
      int d=a,e=b,f;
  if(a<b)
    swap(a,b);
  int c,m=1;
  while(m){
    c=a%b;
    if(c==0){
       f=b;
      m--;
    }
    else{
      a=b;
      b=c;
 }
  }
  return f;
  }
signed main(){
  int a,c,d=0;
  cin>>a;
  vector<int> b(a),e;
  fo(i,a)
    cin>>b[i];
  Sort(b);
  for(int i=0;i<a;i=i){
    c=b[i];
    d=0;
    while(i<a){
      if(b[i]==c)
        d++;
      else
        break;
    }
    if(d>=2)
      e.push_back();
  }
  rev(e);
  if(e.size()<2)
    cout<<0<<endl;
  else
    cout<<e[0]*e[1]<<endl;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:75:18: error: no matching function for call to 'std::vector<long long int>::push_back()'
   75 |       e.push_back();
      |       ~~~~~~~~~~~^~
In file included from /usr/include/c++/14/vector:66,
                 from /usr/include/c++/14/functional:64,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:53,
                 from a.cc:1:
/usr/include/c++/14/bits/stl_vector.h:1283:7: note: candidate: 'void std::vector<_Tp, _Alloc>::push_back(const value_type&) [with _Tp = long long int; _Alloc = std::allocator<long long int>; value_type = long long int]'
 1283 |       push_back(const value_type& __x)
      |       ^~~~~~~~~
/usr/include/c++/14/bits/stl_vector.h:1283:7: note:   candidate expects 1 argument, 0 provided
/usr/include/c++/14/bits/stl_vector.h:1300:7: note: candidate: 'void std::vector<_Tp, _Alloc>::push_back(value_type&&) [with _Tp = long long int; _Alloc = std::allocator<long long int>; value_type = long long int]'
 1300 |       push_back(value_type&& __x)
      |       ^~~~~~~~~
/usr/include/c++/14/bits/stl_vector.h:1300:7: note:   candidate expects 1 argument, 0 provided
Language: C++

#include <bits/stdc++.h>
using namespace std;
#define REP(i,a) for(int i = 0; i < (a); i++)
typedef long long ll;
typedef pair<ll, int> P;
const int INF = 1e9;
const int MOD = 1e9 + 7;

int main(){
	int n;
	cin >> n;
	ll a;
	map<ll, int> mp;
	REP(i,n){
		cin >> a;
		mp[a]++;
	}
	ll line1 = 0,line2 = 0;
	for(auto i : mp){
		if(i.second >= 4){
			if(i.first > line1){
				line1 = i.first;
				line2 = i.second;
			}else if(i.first > line2) line 2 = i.first;
		}else if(i.second >= 2){
			if(i.first > line1){
				line2 = line1;
				line1 = i.first;
			}else if(i.first > line2) line2 = i.first;
		}
	}
	cout << line1 * line2 << endl;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:24:51: error: 'line' was not declared in this scope; did you mean 'line2'?
   24 |                         }else if(i.first > line2) line 2 = i.first;
      |                                                   ^~~~
      |                                                   line2
Language: C++

#include<iostream>
#include<cstring>
#include<cmath>
#include<queue>
#include<cstdio>
#include<algorithm>
#define LL long long
#define INF 1ll<<60
using namespace std;
const int N=2e5+100;
const int M=4e5+100;
const int mod=1e9+7;
int arr[N];
int tmp[N];
int index[N],num[N];
int main() {
	
	int n;
	while(cin>>n){
		memset(num,0,sizeof(num));
		memset(tmp,0,sizeof(tmp));
		for(int i=1;i<=n;i++){
			
			cin>>arr[i];
			tmp[i]=arr[i];
		}
		sort(tmp+1,tmp+1+n);
		int tot=unique(tmp+1,tmp+1+n)-tmp-1;
		//cout<<tot<<endl;
		for(int i=1;i<=n;i++){
			index[i]=lower_bound(tmp+1,tmp+1+tot,arr[i])-tmp;
		}
		
		for(int i=1;i<=n;i++){
			num[index[i]]++;
		}
		LL l=0,r=0,s=1;
		for(int i=tot;i>=1;i--){
			if(num[i]<2)continue;
			else{
				if(l==0)l=tmp[i];
				else {
					r=tmp[i];
					break;
				}
			}
		}
		cout<<l*r<<endl;
	}
	return 0;
}


Compiler output:
a.cc:15:12: error: 'int index [200100]' redeclared as different kind of entity
   15 | int index[N],num[N];
      |            ^
In file included from /usr/include/string.h:462,
                 from /usr/include/c++/14/cstring:43,
                 from a.cc:2:
/usr/include/strings.h:50:20: note: previous declaration 'const char* index(const char*, int)'
   50 | extern const char *index (const char *__s, int __c)
      |                    ^~~~~
a.cc: In function 'int main()':
a.cc:31:30: error: invalid types '<unresolved overloaded function type>[int]' for array subscript
   31 |                         index[i]=lower_bound(tmp+1,tmp+1+tot,arr[i])-tmp;
      |                              ^
a.cc:35:34: error: invalid types '<unresolved overloaded function type>[int]' for array subscript
   35 |                         num[index[i]]++;
      |                                  ^
Language: C++

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




int main(){
  int n;
  cin >>n;
  map<int,int>s;
  long long ma1=0;
  long long ma2=0;
  long long ma3=0;
  for(int i=0;i<n;i++){
    int a;
    cin>>a;
    s[a]++;
    int b= s.at(a);
    if(b>=4){
      ma1=max(ma1,a);
    }
    if(b>=2&&a!=ma2&&a!=ma3){
      if(a>ma2){
        ma3=ma2;
        ma2=a;
      }
      else if(a>ma3){
        ma3=a;
      }
    }
  }
  cout << max(ma1*ma1,ma3*ma2)<<endl;
  cout << ma1 << " " << ma2<< " " << ma3;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:20:14: error: no matching function for call to 'max(long long int&, int&)'
   20 |       ma1=max(ma1,a);
      |           ~~~^~~~~~~
In file included from /usr/include/c++/14/algorithm:60,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:51,
                 from a.cc:1:
/usr/include/c++/14/bits/stl_algobase.h:257:5: note: candidate: 'template<class _Tp> constexpr const _Tp& std::max(const _Tp&, const _Tp&)'
  257 |     max(const _Tp& __a, const _Tp& __b)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:257:5: note:   template argument deduction/substitution failed:
a.cc:20:14: note:   deduced conflicting types for parameter 'const _Tp' ('long long int' and 'int')
   20 |       ma1=max(ma1,a);
      |           ~~~^~~~~~~
/usr/include/c++/14/bits/stl_algobase.h:303:5: note: candidate: 'template<class _Tp, class _Compare> constexpr const _Tp& std::max(const _Tp&, const _Tp&, _Compare)'
  303 |     max(const _Tp& __a, const _Tp& __b, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:303:5: note:   candidate expects 3 arguments, 2 provided
In file included from /usr/include/c++/14/algorithm:61:
/usr/include/c++/14/bits/stl_algo.h:5706:5: note: candidate: 'template<class _Tp> constexpr _Tp std::max(initializer_list<_Tp>)'
 5706 |     max(initializer_list<_Tp> __l)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5706:5: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_algo.h:5716:5: note: candidate: 'template<class _Tp, class _Compare> constexpr _Tp std::max(initializer_list<_Tp>, _Compare)'
 5716 |     max(initializer_list<_Tp> __l, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5716:5: note:   template argument deduction/substitution failed:
a.cc:20:14: note:   mismatched types 'std::initializer_list<_Tp>' and 'long long int'
   20 |       ma1=max(ma1,a);
      |           ~~~^~~~~~~
Language: C++

#include<bits/stdc++.h>
using namespace std;
int main(){
  int n;cin>>n;
  vector<int>a(n);
  for(int i=0;i<n;i++)cin>>a[i];
  sort(a.begin(),a.end());
  int b=0,c=0;
  for(int n-1;i>0;i--){
    if(b==0){
      if(a[i]==a[i-1])b=a[i];
    }
    else
      if(a[i]==a[i-1]&&b>a[i]){
        c=a[i];
      }
    if(c&&b)break;
  }
  cout<<(long long)b*c<<endl;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:9:12: error: expected ';' before '-' token
    9 |   for(int n-1;i>0;i--){
      |            ^
      |            ;
a.cc:9:15: error: 'i' was not declared in this scope
    9 |   for(int n-1;i>0;i--){
      |               ^
a.cc:9:18: error: expected ')' before ';' token
    9 |   for(int n-1;i>0;i--){
      |      ~           ^
      |                  )
a.cc:9:19: error: 'i' was not declared in this scope
    9 |   for(int n-1;i>0;i--){
      |                   ^
Language: C++

#include <iostream>
#include <vector>
#include <map>
#include <string>
#include <algorithm>
#include <stack>
#include <cmath>
#include <utility>

int main()
{
    using namespace std;

    map<int, int> length2Count;

    int n;
    cin >> n;
    for (int i = 0; i < n; ++i)
    {
        int in;
        cin >> in;
        length2Count[in]++;
    }

    vector<ll> usable;
    for (auto l2c : length2Count)
    {
        auto c = l2c.second;
        if (c >= 4)
            usable.push_back(l2c.first);
        if (c >= 2)
            usable.push_back(l2c.first);
    }

    sort(usable.rbegin(), usable.rend());

    if (usable.size() < 2)
    {
        cout << 0 << endl;
    }
    else
    {
        cout << usable[0] * usable[1] << endl;
    }
    

    return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:25:12: error: 'll' was not declared in this scope
   25 |     vector<ll> usable;
      |            ^~
a.cc:25:14: error: template argument 1 is invalid
   25 |     vector<ll> usable;
      |              ^
a.cc:25:14: error: template argument 2 is invalid
a.cc:30:20: error: request for member 'push_back' in 'usable', which is of non-class type 'int'
   30 |             usable.push_back(l2c.first);
      |                    ^~~~~~~~~
a.cc:32:20: error: request for member 'push_back' in 'usable', which is of non-class type 'int'
   32 |             usable.push_back(l2c.first);
      |                    ^~~~~~~~~
a.cc:35:17: error: request for member 'rbegin' in 'usable', which is of non-class type 'int'
   35 |     sort(usable.rbegin(), usable.rend());
      |                 ^~~~~~
a.cc:35:34: error: request for member 'rend' in 'usable', which is of non-class type 'int'
   35 |     sort(usable.rbegin(), usable.rend());
      |                                  ^~~~
a.cc:37:16: error: request for member 'size' in 'usable', which is of non-class type 'int'
   37 |     if (usable.size() < 2)
      |                ^~~~
a.cc:43:23: error: invalid types 'int[int]' for array subscript
   43 |         cout << usable[0] * usable[1] << endl;
      |                       ^
a.cc:43:35: error: invalid types 'int[int]' for array subscript
   43 |         cout << usable[0] * usable[1] << endl;
      |                                   ^
Language: C++

#include<bits/stdc++.h>
#define all(x) (x).begin(),(x).end()
typedef long long ll;
#define rep(i,n) for(ll i=0, i##_len=(n); i<i##_len; ++i)
#define REP(i,num,n) for(ll i=num, i##_len=(n); i<i##_len; ++i)
using namespace std;

int main(void){
    ll N;
    cin >> N;
    ll A;
    map<ll,ll> nums;
    rep(i,N) {
      cin >> A;
      ++nums[A];
    }
    ll side = 0;
    ll side2 = 0;
    ll ans = 0;
    for(auto itr = nums.begin(); itr != nums.end(); ++itr){
        if(side != 0 && itr->second >= 2){
          side2 = itr->first;
          chmax(ans, side * side2);
          side = max(side, side2);
          side2 = 0;
        }
        else if(itr->second >= 2){
           side = itr->first; 
        }
    }
    cout << ans << endl;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:23:11: error: 'chmax' was not declared in this scope
   23 |           chmax(ans, side * side2);
      |           ^~~~~
Language: C++

#include <bits/stdc++.h>
#define REP(i,n) for(int i=0;i<n;i++)
#define REPP(i,n) for(int i=1;i<=n;i++)
const double PI = acos(-1);
const double EPS = 1e-15;
long long INF=(long long)1E17;
#define i_7 (long long)(1E9+7)
long mod(long a){
    long long c=a%i_7;
    if(c>=0)return c;
    return c+i_7;
}
using namespace std;
bool prime(int n){
  if(n==1){
    return false;
  }else if(n==2){
    return true;
  }else{
    for(int i=2;i<=sqrt(n);i++){
      if(n%i==0){
        return false;
      }
    }
    return true;
  }
}

long long gcd(long long a, long long b){
  if(a<b){
    swap(a,b);
  }
  if(a%b==0){
    return b;
  }else{
    return gcd(b,a%b);
  }
}
 
long long lcm(long long x, long long y){
  return (x/gcd(x,y))*y;
}
 
class UnionFind {
    public:
    //各頂点の親の番号を格納する。その頂点自身が親だった場合は-(その集合のサイズ)を入れる。
    vector<int> Parent;
    
    //クラスを作るときは、Parentの値を全て-1にする。
    //以下のようにすると全てバラバラの頂点として解釈できる。
    UnionFind(int N) {
        Parent = vector<int>(N, -1);
    }
    
    //Aがどのグループに属しているか調べる
    int root(int A) {
        if (Parent[A] < 0) return A;
        return Parent[A] = root(Parent[A]);
    }
    
    //自分のいるグループの頂点数を調べる
    int size(int A) {
        return -Parent[root(A)];//先祖をrootで取っておきたい。
    }
    
    //AとBをくっ付ける
    bool connect(int A, int B) {
        //AとBを直接つなぐのではなく、root(A)にroot(B)をくっつける
        A = root(A);
        B = root(B);
        if (A == B) {
            //すでにくっついてるからくっ付けない
            return false;
        }
        
        //大きい方(A)に小さいほう(B)をくっ付けたい
        //大小が逆だったらAとBをひっくり返す。
        if (size(A) < size(B)) swap(A, B);
        
        //Aのサイズを更新する
        Parent[A] += Parent[B];
        //Bの親をAに変更する
        Parent[B] = A;
        
        return true;
    }
};

int main(){
  int n;
  cin>>n;
  map<int,int> mp;
  int a;
  REP(i,n){
    mp[a]++;
  }
  vector<int> edge;
  for(p:mp){
    if(p.second%2==0){
      REP(i,p.second/2){
        edge.push_back(p.first);
      }
    }
  }
  sort(edge.begin(),edge.end(),greater<int>);
  long long ans;
  ans = (long long)edge[0]*edge[1];
  cout<<ans<<endl;
  return 0;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:98:8: error: found ':' in nested-name-specifier, expected '::'
   98 |   for(p:mp){
      |        ^
      |        ::
a.cc:98:7: error: 'p' has not been declared
   98 |   for(p:mp){
      |       ^
a.cc:105:44: error: expected primary-expression before ')' token
  105 |   sort(edge.begin(),edge.end(),greater<int>);
      |                                            ^
a.cc:106:3: error: expected primary-expression before 'long'
  106 |   long long ans;
      |   ^~~~
a.cc:105:46: error: expected ')' before 'long'
  105 |   sort(edge.begin(),edge.end(),greater<int>);
      |                                              ^
      |                                              )
  106 |   long long ans;
      |   ~~~~                                        
a.cc:98:6: note: to match this '('
   98 |   for(p:mp){
      |      ^
a.cc:107:3: error: 'ans' was not declared in this scope; did you mean 'abs'?
  107 |   ans = (long long)edge[0]*edge[1];
      |   ^~~
      |   abs
Language: C++

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

int main() {
    int N;
    cin >> N;
    vector<int> A(N);
    for (int i = 0; i < N; i++)
        cin >> A[i];
    sort(A.begin(), A.end(), greater<int>());

    vector<int> v;
    int pre = A[0], cnt = 1;
    for (int i = 1; i < N; i++) {
        if (A[i] == pre) {
            cnt++;
            if (cnt == 2) {
                v.push_back(A[i]);
                cnt = 0;
            }
        } else {
            cnt = 1;
        }
        pre = A[i];
    }
    cout << (long long)v[0] * v[1] << endl;
    return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:11:5: error: 'sort' was not declared in this scope; did you mean 'short'?
   11 |     sort(A.begin(), A.end(), greater<int>());
      |     ^~~~
      |     short
Language: C++

#include<iostream>
#include<vector>
#include<queue>
#include<set>
#include<map>
#include<string>
#include<cmath>
#include<algorithm>
using namespace std;
using ll = long long;
#define what(x) cerr << #x << " is " << x << endl;

int main(){
    int N;
    cin >> N;
    vector<int> A(N);
    for(int i = 0; i < N; ++i) {
        cin >> A[i];
    }
    map<int, int> m;
    for(int i = 0; i < N; ++i) {
        m[A[i]]++;
    }
    int x = -1;
    int y = -1;
    for(auto & it = m.rbegin(); it != m.rend(); it = next(it)) {
        if (it->second >= 2) {
            x = it->first;
            it->second -= 2;
            break;
        }
    }
    for(auto & it = m.rbegin(); it != m.rend(); it = next(it)) {
        if (it->second >= 2) {
            y = it->first;
            break;
        }
    }
    if (x == -1 || y == -1) {
        cout << 0 << endl;
    }
    else {
        cout << x * y << endl;
    }
    return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:26:29: error: cannot bind non-const lvalue reference of type 'std::reverse_iterator<std::_Rb_tree_iterator<std::pair<const int, int> > >&' to an rvalue of type 'std::map<int, int>::reverse_iterator' {aka 'std::reverse_iterator<std::_Rb_tree_iterator<std::pair<const int, int> > >'}
   26 |     for(auto & it = m.rbegin(); it != m.rend(); it = next(it)) {
      |                     ~~~~~~~~^~
a.cc:33:29: error: cannot bind non-const lvalue reference of type 'std::reverse_iterator<std::_Rb_tree_iterator<std::pair<const int, int> > >&' to an rvalue of type 'std::map<int, int>::reverse_iterator' {aka 'std::reverse_iterator<std::_Rb_tree_iterator<std::pair<const int, int> > >'}
   33 |     for(auto & it = m.rbegin(); it != m.rend(); it = next(it)) {
      |                     ~~~~~~~~^~
Language: C++

#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <iterator>
#include <map>
#include <cmath>
using namespace std;
typedef long long ll;
//typedef pair<ll, ll> P;

template<typename T>auto& operator<<(ostream &s, const vector<T> &v) {
   s << v.size() << " [";
   for (auto e:v) {
      s << e << "\t";
   }
   s << "]";
   return s;
}
template<typename T, typename U>auto& operator<<(ostream &s, const map<T,U> &m) {
   s << "[";
   for (auto i:v) {
      s << "(" << v->first << ", " << v->second << ")\t";
   }
   s << "]";
   return s;
}
#define rep(i, m) for(ll i=0;i<(m);i++)
#define rep1(i, m) for(ll i=1;i<=(m);i++)
#define FOR(i, a, b) for(ll i=(a);i<(b);i++)
//debug
#define dump(x)  cerr << #x << " = " << (x) << endl;
#define debug(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ")" << " " << __FILE__ << endl;
#define INFI 1000000007
map<int, int> c;
//https://cpprefjp.github.io/reference/algorithm/unique.html
int main() {
   int N; cin >> N;
   int m;
   map<int,int> c;
   c[0] = 4; // 最後まで見つからなかったとき0 を返すため
   
   rep(i, N) {
      cin >> m;
      c[m]++;
   }
   int prev = -1;
   // 大きいものから見ていく
   for (auto i=c.end()--;i!=c.begin()--;i--) {
      // 4個以上なら決着
      if (i->second >= 4) {
         cout << i->first * i->first << endl;
         return 0;
      }
      // 2個以上なら次に2個以上なものと組み合わせる. ソースコードが若干気持ち悪い
      if (i->second >= 2) {
         if (prev < 0) {
            prev = i->first;
         } else {
            cout << i->first * prev << endl;
            return 0;
         }
      }
   }
}

Compiler output:
a.cc: In function 'auto& operator<<(std::ostream&, const std::map<T, U>&)':
a.cc:22:16: error: 'v' was not declared in this scope
   22 |    for (auto i:v) {
      |                ^
Language: Java


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

/* Name of the class has to be "Main" only if the class is public. */
publi class Main
{
     
	public static void main (String[] args) throws java.lang.Exception
	{
		// your code goes here
		FastReader sc=new FastReader();
// 		constructST(a,n);RMQ(n, qs, qe)
        // sieveOfEratosthenes();
//		Stack<Character> st=new Stack <> ();
		int n=sc.nextInt(),a[]=new int[n],i,flag1=0,flag2=0;
      	long l=0,b=0;
		for(i=0;i<n;i++)
			a[i]=sc.nextInt();
		Arrays.sort(a);
		for(i=n-1;i>0;i--) {
			if(a[i]==a[i-1] && flag1==0) {
				l=a[i];flag1=1;
			}
			if(a[i]==a[i-1] && a[i]!=l && flag2==0) {
				b=a[i];flag2=1;
			}
		}
		if(flag1==0 || flag2==0)
			System.out.println("0");
		else 
			System.out.println(l*b);
	}
	static int lower_bound(int a[],int x){
         int n=a.length,low=0,high=n-1,res=-1;
         while(low<=high){
             int mid=(low+high)>>1;
             if(a[mid]>=x){
                res=mid;high=mid-1;
             }
             else 
                low=mid+1;
         }
         return res;
     }
      static int upper_bound(int a[],int x){
          int n=a.length,low=0,high=n-1,res=-1;
          while(low<=high){
              int mid=(low+high)>>1;
              if(a[mid]<=x){
                  res=mid;low=mid+1;
              }
              else 
                  high=mid-1;
          }
          return res;
      }
      static long modexpo(long x,long n,long m){
        if(n==0)
            return 1;
        else if(n%2==0)
            return (modexpo(((x%m)*(x%m))%m,n/2,m))%m;
        else
            return ((x%m)*((modexpo(((x%m)*(x%m))%m,(n-1)/2,m))%m))%m;
      } 
       static int gcd(int a,int b){
           if(b==0)
              return a;
           else 
              return gcd(b,a%b);
       }
       static long gcd(long a,long b){
           if(b==0)
              return a;
           else 
              return gcd(b,a%b);
       }
	 static class FastReader{
          BufferedReader in;
          StringTokenizer st;
          public FastReader(){
              in=new BufferedReader(new InputStreamReader(System.in));
          }
          String next(){
              while(st==null || !st.hasMoreElements()){
                  try{
                      st=new StringTokenizer(in.readLine());
                  }
                  catch(IOException e){
                      e.printStackTrace();
                  }
               }
               return st.nextToken();
            }
            int nextInt(){
                return Integer.parseInt(next());
            }
            long nextLong(){
                return Long.parseLong(next());
            }
            double nextDouble(){
                return Double.parseDouble(next());
            }
            String nextLine(){
            String str19 = "";
            try{
                str19 = in.readLine();
            }
            catch (IOException e){
                e.printStackTrace();
             }
            return str19;
        }
      }    
}


Compiler output:
Main.java:7: error: class, interface, enum, or record expected
publi class Main
^
1 error
Language: C++

#include<bits/stdc++.h>
using namespace std;
int main(){
  int n;
  cin>>n;
  vector<int> a(n);
  for(int i=0;i<n;i++){
    cin>>c[i];
  }
  sort(a.begin(),a.end());
  reverse(a.begin(),a.end());
  int m=a[0],c=1,mm;
  bool f=true;
  for(int i=1;i<n;i++){
    if(m==a[i]){
      c++;
    }else{
      if(c>=4&&f){
        cout<<m*m;
        return 0;
      }else if(c>=2){
        mm=m;
        f=false;
      }else if(c>=2&&!f){
        cout<<m*mm;
        return 0;
      }
      c=1;
      m=a[i];
    }
  }
  if(c>=4&&f){
    cout<<m*m;
  }else if(c>=2&&!f){
    cout<<m*mm;
  }else{
    cout<<0;
  }
}

Compiler output:
a.cc: In function 'int main()':
a.cc:8:10: error: 'c' was not declared in this scope
    8 |     cin>>c[i];
      |          ^
Language: C++

#include<bits/stdc++.h>
using namespace std;
#define ALL(obj) (obj).begin(), (obj).end()
#define FOR(i, a, b) for(int i = (a); i < (b); ++i)
#define REP(i, n) for(int i = 0; i < (n); ++i)

#define endl "\n"
#define pb push_back
#define elif else if
#define cout_db cout << fixed

#define MOD 1000000007
 
const int dx[]={1,0,-1,0}, dy[]={0,-1,0,1};
const int dx_8[]={1,1,0,-1,-1,-1,0,1}, dy_8[]={0,-1,-1,-1,0,1,1,1};

typedef long long ll;

template <typename T>
inline T GCD(T a,T b){T c;while(b!=0){c=a%b;a=b;b=c;}return a;}
template <typename T>
inline T LCM(T a,T b){T c=GCD(a,b);a/=c;return a*b;}
template <typename T>
inline T nCr(T a,T b){T i,r=1;for(i=1;i<=b;i++){r*=(a+1-i);r/=i;}return r;}
template <typename T>
inline T nHr(T a,T b){return nCr(a+b-1,b);}
template <typename T>
inline T POW(T a,T b){int i,r=1;for(i=1;i<=b;i++){r*=a;}return r;}

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

	int n
	ll a[100000];
	cin >> n;
	REP(i, n) cin >> a[i];

	map<ll, ll> mp;
	REP(i, n) mp[a[i]]++;

	sort(a, a+n);

	for(int i = n-1;i >= 0;i--){
		if(mp[a[i]] >= 4){
			cout << a[i] * a[i] << endl;
			return 0;
		}
		else if(mp[a[i]] >= 2){
			for(int j = n-1;j >= 0;j--){
				if(a[j] < a[i] and mp[a[j]] >= 2){
					cout << a[i] * a[j] << endl;
					return 0;
				}
			}
		}
	}
	cout << 0 << endl;
	
	return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:35:9: error: expected initializer before 'll'
   35 |         ll a[100000];
      |         ^~
a.cc:36:16: error: 'n' was not declared in this scope; did you mean 'yn'?
   36 |         cin >> n;
      |                ^
      |                yn
a.cc:37:26: error: 'a' was not declared in this scope
   37 |         REP(i, n) cin >> a[i];
      |                          ^
a.cc:40:22: error: 'a' was not declared in this scope
   40 |         REP(i, n) mp[a[i]]++;
      |                      ^
a.cc:42:14: error: 'a' was not declared in this scope
   42 |         sort(a, a+n);
      |              ^
Language: C++

#include <iostream>
using namespace std;
 
int main() {
    int n, a[100000], x, y, k;
    cin >> n;
    for(int i = 0; i < n; i++) cin >> a[i];
    sort(a, a + n, greater<>());
    for(k = 0; k < n && x != a[k]; x = a[k++]) ;
    for(k++; k < n && y != a[k]; y = a[k++]) ;
    if (k == n) y = 0;
    cout << (long long)x * y << endl;
    return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:8:5: error: 'sort' was not declared in this scope; did you mean 'short'?
    8 |     sort(a, a + n, greater<>());
      |     ^~~~
      |     short
Language: Java

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */

/**
 *
 * @author anvit
 */
import java.util.*;
public class ColoringDominoes {
    public static void main(String[] args){
        Scanner in=new Scanner(System.in);
        int n=in.nextInt();
        String s1=in.next();
        String s2=in.next();
        //int[] arr=new int[n];
        int p=1;
        if(s1.charAt(0)==s2.charAt(0))
            p=3;
        else if(s1.charAt(0)==s1.charAt(1))
            p=6;
        for(int i=1;i<s1.length();i++){
            if(i<s1.length()-1 && s1.charAt(i)==s1.charAt(i+1)){
                p*=2%1000000007;
            }
            else if(s1.charAt(i)==s2.charAt(i)){
                if(s1.charAt(i-1)==s2.charAt(i-1))
                    p*=2%1000000007;
            }
            p=p%1000000007;
        }
        System.out.println(p);
    }
}


Compiler output:
Main.java:12: error: class ColoringDominoes is public, should be declared in a file named ColoringDominoes.java
public class ColoringDominoes {
       ^
1 error
Language: C++

#include<stdio.h>
void sort(int a[], int n);
int main()
{
	int n, a[100000], i, c[2] = { 0, 0 }, e=0;
	scanf("%d", &n);
	for (i = 0; i < n; i++){
		scanf("%d", &a[i]);
	}
	sort(a, n);
	for (i = n - 1; i >= 0; i--){
		if (a[i] == a[i - 1]){
			c[e] = a[i];
			e++;
			i++;
		}
		if (e>1){
			break;
		}
	}
	printf("%d", c[0] * c[1]);
	return 0;
}
void sort(int a[], int n){
	int i, j, t;
	for (i = 0, i < n - 1; i++){
		for (j = n-1; j>i; j--){
			if (a[j - 1]>a[j]){
				t = a[j-1];
				a[j - 1] = a[j];
				a[j] = t;
			}
		}
	}
}

Compiler output:
a.cc: In function 'void sort(int*, int)':
a.cc:26:35: error: expected ';' before ')' token
   26 |         for (i = 0, i < n - 1; i++){
      |                                   ^
      |                                   ;
Language: C++

#include <iostream>
#include <algorithm>
#include <cmath>
#include <limits>
#include <vector>
#include <cstdio>
#include <bits/stdc++.h>
#include <set>
#include <map>
#include <stdio.h>
using namespace std;
using ll = int long long;
map <int ,int> mpa,mpb;

int main (){
  ll N;
  cin  >> N;
  ll a[N];
  ll ans=0;
  ll l=1,r=0;
  for(ll i=0;i<N;i++){
    cin >> a[i]
  }
  sort(a,a+N);
  int k=1;
  for(ll i=1;i<N;i++){
    if(a[i-1]==a[i]){
      k++
      (r<l? l:r)=a[i];
      if(k>=4){
        l=r=a[i];
      }
      continue
    }
    else{
      k=1;
    }
  }
  ans=l*r;
  cout << ans;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:22:16: error: expected ';' before '}' token
   22 |     cin >> a[i]
      |                ^
      |                ;
   23 |   }
      |   ~             
a.cc:29:7: error: expression cannot be used as a function
   28 |       k++
      |       ~~~
   29 |       (r<l? l:r)=a[i];
      |       ^~~~~~~~~~
a.cc:33:15: error: expected ';' before '}' token
   33 |       continue
      |               ^
      |               ;
   34 |     }
      |     ~
Language: C++

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

int main(){
    int h,w;
    cin>>h>>w;
    vector<string> s(h);
    for(int i=0;i<h;i++) cin>>s[i];

    vector<vector<int>> f(h-1,vector<int>(w-1,0));
    for(int i=0;i<h-1;i++){
        for(int j=0;j<w-1;j++){
            f[i][j]=s[i][j]^s[i+1][j+1]^s[i][j+1]^s[i+1][j]);
        }
    }
    vector<vector<int>> height(h,vector<int>(w,0));
    for(int i=0;i<h-1;i++){
        for(int j=0;j<w-1;j++){
            if(!f[i][j]) height[i+1][j]=0;
            else height[i+1][j]=height[i][j]+1;
        }
    }
    /*
    for(int i=0;i<h;i++){
        for(int j=0;j<w;j++){
            cout<<height[i][j];
        }
        cout<<endl;
    }
    */
    int res=max(h,w);
    for(int i=0;i<h;i++){
        stack<pair<int,int>> st;
        st.push(make_pair(0,-1));
        for(int j=0;j<w;j++){
            pair<int,int> ret;
            while(ret=st.top(),height[i][j]<ret.first){
                res=max((j-ret.second+1)*(ret.first+1),res);
                st.pop();
            }
            if(ret.first<height[i][j]) st.push(make_pair(height[i][j],j));
        }
    }
    cout<<res<<endl;
    return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:13:60: error: expected ';' before ')' token
   13 |             f[i][j]=s[i][j]^s[i+1][j+1]^s[i][j+1]^s[i+1][j]);
      |                                                            ^
      |                                                            ;
Language: C++

// ------------------------------------
// Date:2018/ 3/19
// Problem:Make a Rectangle c.cpp
//
// ------------------------------------

#include <bits/stdc++.h>

using namespace std;

#define EACH(i,a) for (auto& i : a)
#define FOR(i,a,b) for(int i=(int)a;i<(int)b;++i)
#define RFOR(i,a,b) for(int i=(int)b-1;i>=(int)a;--i)
#define REP(i,n) FOR(i,0,n)
#define RREP(i,n) RFOR(i,0,n)
#define ALL(a) (a).begin(),(a).end()
#define debug(x) cerr << #x << ":" << x << "\n";
#define OK(ok) cout << (ok ? "Yes" : "No") <<　"\n";
typedef long long ll;

void CINT(){}
template <class Head,class... Tail>
void CINT(Head&& head,Tail&&... tail) {
  cin >> head; CINT(move(tail)...);
}
#define CIN(...) int __VA_ARGS__;CINT(__VA_ARGS__)
#define LCIN(...) ll __VA_ARGS__;CINT(__VA_ARGS__)
#define SCIN(...) string __VA_ARGS__;CINT(__VA_ARGS__)

static const int MOD = 1e9 + 7;
static const int MAX_N = 1e9 + 1;

ll p[MAX_N];

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

  // fill_n(p, MAX_N, 0);
  CIN(N);
  REP(i, N) {
    CIN(a);
    p[a - 1]++;
  }

  vector< ll > t;
  REP(i, MAX_N) {
    if (p[i] > 1) {
      REP(j, p[i] / 2) {
	t.emplace_back(i + 1);
      }
    }
  }
  ll ans;
  if (t.size() < 2) ans = 0;
  else {
    sort(ALL(t));
    reverse(ALL(t));
    ans = t[0] * t[1];
  }
  cout << ans << endl;
  return 0;
}



Compiler output:
a.cc:18:46: error: extended character 　 is not valid in an identifier
   18 | #define OK(ok) cout << (ok ? "Yes" : "No") <<　"\n";
      |                                              ^
Language: C++

// ------------------------------------
// Date:2018/ 3/19
// Problem:Make a Rectangle c.cpp
//
// ------------------------------------

#include <bits/stdc++.h>

using namespace std;

#define EACH(i,a) for (auto& i : a)
#define FOR(i,a,b) for(int i=(int)a;i<(int)b;++i)
#define RFOR(i,a,b) for(int i=(int)b-1;i>=(int)a;--i)
#define REP(i,n) FOR(i,0,n)
#define RREP(i,n) RFOR(i,0,n)
#define ALL(a) (a).begin(),(a).end()
#define debug(x) cerr << #x << ":" << x << "\n";
#define OK(ok) cout << (ok ? "Yes" : "No") <<　"\n";
typedef long long ll;

void CINT(){}
template <class Head,class... Tail>
void CINT(Head&& head,Tail&&... tail) {
  cin >> head; CINT(move(tail)...);
}
#define CIN(...) int __VA_ARGS__;CINT(__VA_ARGS__)
#define LCIN(...) ll __VA_ARGS__;CINT(__VA_ARGS__)
#define SCIN(...) string __VA_ARGS__;CINT(__VA_ARGS__)

static const int MOD = 1e9 + 7;
static const int MAX_N = 1e5 + 1;

int p[MAX_N];

int main()
{

  fill_n(p, MAX_N, 0);
  int N;
  scanf("%d" &N);
  REP(i, N) {
    int a;
    scanf("%d", &a);
    p[a - 1]++;
  }

  vector< int > t;
  REP(i, MAX_N) {
    if (p[i] > 1) {
      REP(j, p[i] / 2) {
	t.push_back(i + 1);
      }
    }
  }
  ll ans;
  if (t.size() < 2) ans = 0;
  else {
    sort(ALL(t));
    ans = t[t.size() - 1] * t[t.size() - 2];
  }
  cout << ans << endl;
  return 0;
}



Compiler output:
a.cc:18:46: error: extended character 　 is not valid in an identifier
   18 | #define OK(ok) cout << (ok ? "Yes" : "No") <<　"\n";
      |                                              ^
a.cc: In function 'int main()':
a.cc:40:14: error: invalid operands of types 'const char [3]' and 'int' to binary 'operator&'
   40 |   scanf("%d" &N);
      |         ~~~~ ^~
      |         |     |
      |         |     int
      |         const char [3]
Language: C++

#include <iostream>
#include <cstdio>
#include <algorithm>
using namespace std;

const int N = 100006;

int a[N];

int main ()
{
    int n;
    scanf("%d",&n);
    for (int i=1;n>=i;i++)
    {
        scanf("%d",&a[i]);
    }
    sort(a+1,a+n+1);
    long long ans=0;
    vector<int> cans;
    for (int i=n;i>=1;i--)
    {
        if (a[i] == a[i-1])
        {
            cans.push_back(a[i]);
            --i;
        }
    }
    if (cans.size() >= 2)
    {
        cout << cans[0] * 1LL * cans[1] << endl;
    }
    else cout << 0 <<endl;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:20:5: error: 'vector' was not declared in this scope
   20 |     vector<int> cans;
      |     ^~~~~~
a.cc:4:1: note: 'std::vector' is defined in header '<vector>'; this is probably fixable by adding '#include <vector>'
    3 | #include <algorithm>
  +++ |+#include <vector>
    4 | using namespace std;
a.cc:20:12: error: expected primary-expression before 'int'
   20 |     vector<int> cans;
      |            ^~~
a.cc:25:13: error: 'cans' was not declared in this scope; did you mean 'ans'?
   25 |             cans.push_back(a[i]);
      |             ^~~~
      |             ans
a.cc:29:9: error: 'cans' was not declared in this scope; did you mean 'ans'?
   29 |     if (cans.size() >= 2)
      |         ^~~~
      |         ans
Language: C++

#include <memory.h>
using namespace std;

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

int main(void){
	int N;
	int a;
	pair<int, int> A[100000];
	long long max = -1, second = -1;
	long long square;

	memset(A, 0, sizeof(A));

	scanf("%d", &N);

	for(int i=0;i<N;i++){
		scanf("%d", &a);
		for(int j=0; j<N; j++){
			if(A[j].first==0){
				A[j].first ++;
				A[j].second = a;
				break;
			}else if(A[j].second==a){
				A[j].first ++;
				break;
			}
		}
	}

	for(int k=0;k<N;k++){
		if(A[k].first>=2){
			if(max<A[k].second){
				max = A[k].second;
				A[k].first -= 2;
			}
		}

		if(A[k].first>=2){
			if(second<A[k].second){
				second = A[k].second;
			}
		}
	}

	square = max*second;

	if( max>0 && second > 0){
		printf("%ld\n", square);
	}else{
		printf("%ld\n", 0);
	}


	return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:10:9: error: 'pair' was not declared in this scope
   10 |         pair<int, int> A[100000];
      |         ^~~~
a.cc:6:1: note: 'std::pair' is defined in header '<utility>'; this is probably fixable by adding '#include <utility>'
    5 | #include <stdlib.h>
  +++ |+#include <utility>
    6 | 
a.cc:10:14: error: expected primary-expression before 'int'
   10 |         pair<int, int> A[100000];
      |              ^~~
a.cc:14:16: error: 'A' was not declared in this scope
   14 |         memset(A, 0, sizeof(A));
      |                ^