#include<iostream>
#include<iomanip>
#include<cmath>
using namespace std;
int main(){
    int st;
    cin >> st;
    if ( st == 1){
        int side;
        cin >> side;
        if( side <= 0 || side > 1000){
            cout << "Invalid input" << endl;
        }
        else{
            cout << fixed << setprecision(3) << (lenght * width) << endl;
        }
        
    }
    else if ( st==2){
        int length,width;
        cin >> length >> width;
        if (length <=0 || length > 1000 || width <= 0 || width > 1000){
           cout << "Invalid input" << endl;
        }
        else{
            double area = M_PI * radius * radius;
            cout << fixed << setprecision(3) << area << endl;
        }
    }
    else{
        cout << "Invalid input" << endl;
    }
}