#include<iostream>
#include<algorithm>
#include<cstring>
#define int long long
using namespace std;
const int N=2e5+5;
int a[N],T,n,c,sum,cnt,i;
signed main(){
    ios::sync_with_stdio(false);
    cin>>T;
    while(T--){
        memset(a,0,sizeof(a));
        cin>>n>>c;
        for(int i=1;i<=n;i++){
            cin>>a[i];
            a[i]+=i;
        }
        sort(a+1,a+n+1);
        i=1,cnt=0;
        while(i<=n&&c>=0){
            c-=a[i];
            ++cnt,++i;
        }
        cout<<cnt-1<<endl;
    }
    return 0;
}

https://codeforces.com/contest/1791/submission/270171406