#include <bits/stdc++.h>
#define pb push_back
#define ll long long
using namespace std;

ll a[1007];
vector<int> v;

void solve() {
    int b,n;
    cin>>b>>n;
    for(int i=0;i<b;i++) cin>>a[i];
    if(n <= b) {
        cout<<n<<"\n";
    }
    else {
        v.clear();
        n-=b;
        int K=0;

        /*
         * LCM
         */
        ll LCM;
        if(b==1) LCM = a[0];
        else if(b==2) LCM = (a[0]*a[1])/__gcd(a[0],a[1]);
        else {
            LCM = (a[0]*a[1])/__gcd(a[0],a[1]);
            for(ll i=3;i<b;i++) {
                LCM = (LCM * a[i])/__gcd(LCM,a[i]);
            }
        }

        /*
         * Cycle
         */
        for(ll tm=1;tm<=LCM;tm++) {
            for(int i=0;i<b;i++) {
                if(tm%a[i]==0) {
                    v.pb(i+1);
                    K++;
                }
            }
        }

        /*
         * Modulo
         */
        n %= K;
        cout<<v[(n+K-1) % K]<<"\n";
    }
}

int main() {
    int t; cin>>t;
    for(int qq=1;qq<=t;qq++) {
        cout<<"Case #"<<qq<<": ";
        solve();
    }
}