#include<bits/stdc++.h> using namespace std; int main(){ int r1,r2; cin>>r1>>r2; printf("%.2f",3.14*r1*r1-3.14*r2*r2); }//1674 /************************************************************** Problem: 1338 User: linmiaoling Language: C++ Result: Accepted Time:8 ms Memory:2072 kb ****************************************************************/