dobri

#include <bits/stdc++.h>

#define i64 long long
#define u64 unsigned long long
#define i32 int
#define u32 unsigned int

#define pii pair<int, int>
#define pll pair<long long, long long>

#define ld long double
#define defmod 1000000007

#define mati64(a,b) vector<vector<i64>>(a, vector<i64>(b, 0));
using namespace std;


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

  int n; cin >> n;
  int a[5050];
  for(int i = 0; i < n; ++i)
    cin >> a[i];
  set<int> lel;
  
  int ans = 0;
  lel.insert(a[0]*2);
  for(int i = 1; i < n; ++i){
    for(int j = 0; j < i; ++j){
      if(lel.count(a[i]-a[j])){
	++ans;
	break;
      }
    }
    lel.insert(2*a[i]);
    for(int j = 0; j < i; ++j)
      lel.insert(a[i]+a[j]);
      
  }
  cout << ans << endl;
  return 0;
}

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: TIME LIMIT EXCEEDED

Test 12

Verdict: TIME LIMIT EXCEEDED

Test 13

Verdict: TIME LIMIT EXCEEDED