#include <bits/stdc++.h>
                    
    using namespace std;
     
    typedef long long ll;
         
    int T, n;
    ll k;
    ll w[1005];
    ll c[1005][1005];
     
    inline void C()
    {
        for(int i = 0; i <= 1000; ++i)
            c[i][i] = 1;
        for(int i = 0; i <= 1000; ++i)
            c[0][i] = 1;
        for(int i = 1; i <= 1000; ++i)
            for(int j = i+1; j <= 1000; ++j)
                c[i][j] = c[i][j-1]+c[i-1][j-1];
    }
     
    int main()
    {
        freopen("NPH.in", "r", stdin);
        freopen("NPH.out", "w", stdout);
                
        ios::sync_with_stdio(false);
        cin.tie(0); cout.tie(0);
        
        cin >> T; 
        C();  
        while(T--)
        {
            cin >> n >> k;
            for(int i = 1; i <= n; ++i)
                cin >> w[i];
            if(n == 1)
            {
                cout << w[1]*k << '\n';
                continue;
            }
            bool p = true;
            for(int i = 1; i <= n; ++i)
                if(w[i] != 1)
                {
                    p = false;
                    break;
                }
            if(p == true)
            {
                ll cnt = n;
                ll num = 0;
                while(k > 0)
                {
                    k -= cnt;
                    num++;
                    cnt += (num+1)*c[num+1][n];
                }
                cout << num << '\n';
            }
            else cout << k << '\n';
        }
            
       	return 0;
    }