dobri

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
int t[5555];
const int MN = 1e7+100;
const int R = 5e6;
int q[MN];
int main() {
    int n;
    cin>>n;
    for(int i = 0 ;i < n; ++i) {
	cin>>t[i];
    }
    int ans = 0;

    for(int i = 0; i < n; ++i) {
	for(int j = 0; j < i; ++j) {
	    if(q[t[i]-t[j]+R]) {
		++ans;
		break;
	    }
	}
	for(int j = 0; j <= i; ++j) {
	    q[t[i]+t[j]+R] = 1;
	}
    }
    cout<<ans<<'\n';
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED