代码如下：

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

int a[105];
int main(){
	int n;
	cin >> n;
	for(int i = 1; i <= n; i++)
	{
		cin >> a[i];
	}
	int ans = 0;
	// sort(a + 1, a + n + 1);
	for(int i = 1; i <= n; i++)
	{
		for(int j = 1; j <= n; j++)
		{
			for(int k = 1; k <= n; k++)
			{
				if(i != j && j != k && i != k)
				{
					if(a[i] == a[j] + a[k])
					{
						ans++;
						// cout << a[i] << " "<< a[j] << " "<< a[k] << endl;
						break;
					}
				}
			}
		}
	}
	cout << ans / 2 << endl;
	return 0;
}