#include<cstdio>

const int N = 1e3;
int T;
int n, d, cost, top, cnt;
int a[N];
inline void solve() {
    if(cost == d) {
        printf("%d\n", cnt);
        return;
    }
    while(cost > d) {
        cost -= top;
        cnt--;
    }
    printf("%d\n", cnt);
    return; 
}
int main() {
    scanf("%d", &T);
    while(T--) {
        scanf("%d %d", &n, &d);
        cost = 0, top =  0, cnt = 0;
        for(int i = 1; i <= n; i++){
            scanf("%d", &a[i]);
            if(cost < d) {
                cost += a[i] * (i - 1);
                cnt += a[i];
                top = i - 1;
            }
        }
        solve();
    }
}