Where is my mistake?

#include<iostream.h>
#include<math.h>
int top(long int x)
{
    long t ;
    t = (long)sqrt(8*x -7);
    t = t*t;
    if (t != 8*x-7 ) return 0;
    else return 1;
}
int main()
{
    long int k;
    int a[65535];
    unsigned short int i;
    long int n;
    cin >> n;
    for( i = 1;i <= n ;i++ )
    {
        cin >>k;
        if (k != 1)
            a[i] = top(k);
        else
            a[i] = 1;
    }
    for (i =1; i<=n; i++) cout << a[i] <<" ";
    return 0;
}