#include <iostream>
#include <fstream>
using namespace std;
int abs(int a){
    return (a>0)?a:-a;
}

ofstream fout("outt.txt");

int heap[10001];
int T,n,x,y;
int main(){
    heap[0]=1;
    for(int i=1;i<=10000;i++){
        heap[i]=heap[i-1]+4*i+1;
    }
    cin>>T;
    fout.precision(10);
    fout<<fixed;
    for(int g=1;g<=T;g++){
        cin>>n>>x>>y;
        if(abs(x)+y==0){
            fout<<"Case #"<<g<<": "<<1<<endl;
            continue;
        }
        if(heap[(abs(x)+y)/2-1]>=n){
            fout<<"Case #"<<g<<": "<<0<<endl;
            continue;
        }
        if(heap[(abs(x)+y)/2]<=n){
            fout<<"Case #"<<g<<": "<<1<<endl;
            continue;
        }
        if(x==0){
            fout<<"Case #"<<g<<": "<<0<<endl;
            continue;
        }
        n-=heap[(abs(x)+y)/2-1];
        if(n>abs(x)+2*y){
            fout<<"Case #"<<g<<": "<<1<<endl;
            continue;
        }
        long double p=1.0,sl=0;
        for(int i=1;i<=n;i++){
            if(i<y+1){
                p*=(long double)(n-i+1);
                p/=i;
            }
            p/=2;
        }
        for(int i=1;i<=n;i++){
            if(i>=y+1){
                p*=(long double)(n-i+1);
                p/=i;
                sl+=p;
            }

        }
        fout<<"Case #"<<g<<": "<<sl<<endl;
    }
}