#include <iostream>
#include <string>
#include <stdlib.h>
using namespace std;
int main (){
float radio, pi, area=0;
cout<<"Digite radio del circulo: ";cin>>radio;
pi=3.1416;
area=pi*(radio*radio);
cout<<"El Area de un circulo es: "<<area<<endl;
system("pause");
return 0;
}