#include <cstdio>
int a[105];
int main()
{
    int n, cnt = 0;
    scanf("%d", &n);
    scanf("%d %d", &a[1], &a[2]);
    for (int i = 3; i <= n; i++)
    {
        scanf("%d", &a[i]);
        for (int j = 2; j < i; j++)
            for (int k = 1; k < j; k++)
                if (a[j] + a[k] == a[i])
                {
                    cnt++;
                    break;
                }
    }
    printf("%d", cnt);
    return 0;
}