#include<iostream> using namespace std; int main(){/** int a;//d scanf("%d",&a); cout<<a; int a; char b; float c; double d; long long e; scanf("%d%c%f%lf%lld",&a,&b,&c,&d,&e); cout<<a<<""<<b<<""<<c<<""<<d<<""<<e<<endl; // 1234 4123 int a,b;//d scanf("%3d%1d",&a,&b); cout<<b<<a; // 12345 54321 int a,b,c,d,e; scanf("%1d%1d%1d%1d%1d",&e,&d,&c,&b,&a); cout<<a<<b<<""<<c<<""<<d<<""<<e<<endl; printf("%s","hello,world\n"); printf("%s%s%s%s%s%s","*\n","**\n","***\n","****\n","*****\n","******\n"); printf("%s","1+2"); printf("%d",1+2); double a,b; scanf("%lf %lf",&a,&b); printf("%.2lf",a/b); **/ double a,pi = 3.1415926; scanf("%lf",&a); printf("%.2lf",pi*a*a); return 0; }