dobri

#include <iostream>

using namespace std;
int t[606060], A[5050];
int main(){
    int n,v=0;
    cin >> n;
    for(int i=0; i<n; ++i) cin >> A[i];
    for(int i=0; i<n-1; ++i){
        for(int j=0; j<=i; ++j){
            t[A[i]+A[j]+300000]=1;
        }
        for(int j=0; j<=i; ++j){
            if(t[A[i+1]-A[j]+300000]) {++v; break;}
        }
    }
    cout << v;
}

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