#include <bits/stdc++.h>
#define int long long
using namespace std;
 
 
void solve() {
	int n,c;
	cin>>n>>c;
	vector<int> v(n);
	for(int i=0;i<n;i++)cin>>v[i];
	vector<int> h(n);
	for(int i=0;i<n;i++){
		h[i]=(i+1)+v[i];
	}
	sort(h.begin(),h.end());
	int cnt=0;
	int i=0;
	while(i<n){
		if(c>=h[i]){
			c-=h[i];
			cnt++;
		}
		else{
			break;
		}
		i++;
	}
	cout<<cnt<<endl;
 
}
 
signed main() {
    int t;
    cin >> t;
    while (t--) {
        solve();
    }
    return 0;
}
 

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MTAKNSA2CjEgMSAxIDEgMQo4IDMyCjEwMCA1MiAxMyA2IDkgNCAxMDAgMzUKMSAxCjUKNCA1CjQgMyAyIDEKNSA5CjIgMyAxIDQgMQo1IDgKMiAzIDEgNCAxCjQgMwoyIDMgNCAxCjQgOQo1IDQgMyAzCjIgMTQKNyA1CjUgNjAwMDAwMDAwCjUwMDAwMDAwMCA0MDAwMDAwMDAgMzAwMDAwMDAwIDIwMDAwMDAwMCAxMDAwMDAwMDAK

10
5 6
1 1 1 1 1
8 32
100 52 13 6 9 4 100 35
1 1
5
4 5
4 3 2 1
5 9
2 3 1 4 1
5 8
2 3 1 4 1
4 3
2 3 4 1
4 9
5 4 3 3
2 14
7 5
5 600000000
500000000 400000000 300000000 200000000 100000000