题解

#include <bits/stdc++.h>
using namespace std;
int n, s = 0, a[10005];
bool js(int b) {
	for (int j = 1; j <= n; j++) {
		for (int k = j; k <= n; k++) {
			if (a[j] + a[k] == b && a[j] != a[k]) {
				return true;
			}
		}
	}
	return false;
}
int main() {
	;
	cin >> n;
	for (int i = 1; i <= n; i++) {
		cin >> a[i];
	}
	for (int i = 1; i <= n; i++) {
		if (js(a[i])) {
			s++;
		}
	}
	cout << s;
	return 0;
}