Juice in the Glass LightOj 1216

In this problem we need to just find a equation,
a equation called conic  frustrum volume:
         
           V  = (pi*h /3) *(R*R + R*r + r*r)

code(c++):

/*
Author : Mohammad Morsalin Hossain
Dept of ICE,NSTU
*/
#include<bits/stdc++.h>
#define ll long long
#define pb push_back
#define mp make_pair
#define ms(x) memset(x,0,sizeof(x))
#define ins insert
#define pi acos(-1)
#define IOS ios::sync_with_stdio(false);
using namespace std;
int main()
{
    IOS
    int test,to=0;
    cin>>test;
    while(test--)
    {
        int r1,r2,h,p;
        cin>>r1>>r2>>h>>p;
        double pr= r2 +(r1-r2)*((double)p/h);
        double v;
        v = (pi*p)*(((double)pr*(double)pr)+((double)pr*(double)r2)+((double)r2*(double)r2))/3.0;
        printf("Case %d: %lf\n",++to,v);
    }
    return 0;
}