Light OJ 1265 / Probability Expected value

/***
 created: 2022-07-08-00.19.17
***/

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
template<typename U> using ordered_set=tree<U, null_type,less<U>,rb_tree_tag,tree_order_statistics_node_update>;
#define ll long long
#define test int tt; cin>>tt; for(int cs=1;cs<=tt;cs++)
#define get_lost_idiot return 0
#define nl '\n'


int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);


    test
    {
        ll n,m,i,j,t,d;

        cin>>t>>d;

        cout<<"Case "<<cs<<": ";

        if(t==0)
        {
            cout<<1<<nl;
        }

        else if(t%2==0)
        {
            double ans=1.00/((t+1.00)*1.00);

            cout<<fixed<<setprecision(10)<<ans<<nl;
        }

        else cout<<0<<nl;
    }


    get_lost_idiot;
}

/*

d1 = (t / t+1)*(t-1 / t)

final winning =(t - 1)/(t + 1)*(t - 3)/(t - 1)*(t - 5)/(t - 3) * 5/7 * 3/5 * 1/3

finally = 1 / (t+1);

*/