#include<stdio.h>
#define PI 3.1415926535897993
int main(){
    int r, h;
    float surfaceAera, volume;
    scanf("%d", &r);
    scanf("%d", &h);
    if(radius < 0){
        printf("Invalid input");
        return o;
    }
    area = PI * radius * radius;
    printf("%.2f", area);
    return 0;
    }