#pragma comment(linker, "/STACK:1024000000,1024000000")
#include <bits/stdc++.h>

typedef long long int LL;

using namespace std;

#define abs(x) ((x)>0?(x):-(x))

const int N = 1e6+7;

/*****************************************************************/
#define create_date1

#ifdef create_date

int k;
void print(LL x){
    for(int i=k-1;i>=0;i--){
        if(x&(1ll<<i)) printf("1");
        else           printf("0");
    }
}

int main(){
    freopen("input8.txt","w",stdout);

    srand(time(NULL)+19970622.);

    int _ = 10;
    printf("%d\n",_);
    for(;_--;){
        k=60; printf("%d\n",k);
        for(int i=1000000/60;i;i--) print(rand()*rand());

        for(int i=1000000-1000000/60*60;i;i--){
            if(rand()%2) printf("1");
            else printf("0");
        }
        puts("");
    }
    return 0;
}
#else

char s[N];
int k;

void print(LL x){
    for(int i=k-1;i>=0;i--){
        if(x&(1ll<<i)) printf("1");
        else           printf("0");
    }
    puts("");
}

int main(){
//    freopen("input8.txt","r",stdin);
//    freopen("output8.txt","w",stdout);

    int _=1,kcase=0;
    scanf("%d",&_);
    while(_--){
        scanf("%d",&k);
        scanf("%s",s);
        int l=strlen(s);
        LL x=0,mx=0;
        for(int i=l-k+1;i<l;i++){
            x<<=1;
            x|= s[i]=='1' ;
        }
        for(int i=l-k;i>=0;i--){
            if(s[i]=='1') x|=1LL<<(k-1);
            mx=max(mx,x);
//            printf("mx = %lld x = %lld ",mx,x);
//            print(x);
            x>>=1;
        }
        printf("Case #%d: %lld\n",++kcase,mx);
//        print(mx);
    }
    return 0;
}
#endif // create_date

/**
10
5
10101110101011101011111
*/