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

const int N = 1e5 + 5;

long long a[N];

long long n, m;
long long f(long long x)
{
    for (int i = 1; i <= n; i++)
    {
        x += a[i];
        if (x < 0)
            x = 0;
        if (x >= m)
            return x;
    }
    return x;
}
int main()
{
    int t;
    cin >> t;
    while (t--)
    {
        scanf("%lld %lld", &n, &m);
        for (int i = 1; i <= n; i++)
            scanf("%lld", &a[i]);
        __int128 x = 0;
        __int128 x1 = f(x);
        __int128 x2 = f(x1);
        if (x1 >= m)
        {
            puts("1");
            continue;
        }
        if (x2 >= m)
        {
            puts("2");
            continue;
        }
        if (x1 == x2)
        {
            puts("-1");
            continue;
        }
        __int128 ONE = x2 - x1;

        __int128 l = 2, r = m / ONE + 1;
        long long ans;
        while (l <= r)
        {
            __int128 mid = l + r >> 1;
            __int128 beg = x1 + (mid - 2) * ONE;
            if (f(beg) >= m)
            {
                ans = mid;
                r = mid - 1;
            }
            else
                l = mid + 1;
        }
        cout << ans << endl;
    }

    return 0;
}