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  1. #include <iostream>
  2. #include <cmath>
  3. using namespace std;
  4. int main() {
  5. double R, r;
  6. cin>>R>>r;
  7. cout<<R*R*M_PI-r*r*M_PI<<endl;
  8. return 0;
  9. }
Success #stdin #stdout 0s 3416KB
stdin
10.2531 1
stdout
327.122