#include<stdio.h>
int main()
#define pi 3.14;
{
double r,area;
scanf("%lf",&r);
area=3.14*r*r;
printf("%lf",area);
return 0;
}
I2luY2x1ZGU8c3RkaW8uaD4KaW50IG1haW4oKQojZGVmaW5lIHBpIDMuMTQ7CnsKZG91YmxlIHIsYXJlYTsKc2NhbmYoIiVsZiIsJnIpOwphcmVhPTMuMTQqcipyOwpwcmludGYoIiVsZiIsYXJlYSk7CnJldHVybiAwOwp9