C :

#include<stdio.h>
#define PI 3.1415926
void main()
{
	double r;
	scanf("%lf",&r);
	printf("%.2f\n",PI*r*r);
	printf("%.2f\n",2*PI*r);
}

C++ :

#include<iostream>
using namespace std;
const float pi(3.1415926);
int main()
{
    float r,s,c;
    cin>>r;
    s=pi*r*r;  
    c=2*pi*r;
    cout.precision(2);
    cout.setf(ios::fixed);
    cout<<s<<endl;
    cout<<c<<endl;
    //system("pause");
    return 0;
}