#include<bits/stdc++.h>
using namespace std;
#define it long long
#define sf(x) scanf("%lld",&x)
#define pf(x) printf("%lld\n",x)
it a[100004];
int main() {
	it t;
	sf(t);
	while (t--) {
		it n, c,cnt=0;
		sf(n);
		sf(c);
		for (it i = 1; i <= n; i++) {
			sf(a[i]);
			a[i] += i;
		}
		sort(a+1, a + n+1);
		for (it i = 1; i <= n; i++) {
			if (c >= 0)cnt++;
			c -= a[i];
		}
		pf(cnt - 1);
	}
	return 0;
}