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

const int N = 100000 + 9;

int a[N];

void solve() {
    int n;
    long long m;
    scanf("%d %lld", &n, &m);
    for (int i = 1; i <= n; ++i) {
        scanf("%d", a + i);
    }
    long long maxv = 0, sum = 0;
    for (int i = 1; i <= n; ++i) {
        sum += a[i];
        maxv = max(maxv, sum);
    }
    long long ans = 0;
    long long x = 0;
    long long _x = 0;
    while (true) {
        int cnt = 0;
        bool f = false;
        for (int i = 1; i <= n; ++i) {
            x += a[i];
            if (x < 0) {
                x = 0;
                ++cnt;
            }
            else if (x >= m) {
                f = true;
                break;
            }
        }
        ++ans;
        if (f) break;
        if (x == _x) {
            ans = -1;
            break;
        }
        if (cnt) {
            _x = x;
        }
        else {
            if (x + maxv >= m) {
                ++ans;
            }
            else {
                ans += (m - x - maxv - 1) / (x - _x) + 2;
            }
            break;
        }
    }
    printf("%lld\n", ans);
}

int main() {
    int T; scanf("%d", &T);
    while (T--) solve();
    return 0;
}