#include <iostream>
#include <cmath>   //para c es math.h
using namespace std;

float getPI( float n ) {
    return n * M_PI;
}

int main () {
    cout << getPI(1) << endl;
    cout << getPI(2) << endl;
    
    cout << getPI(23.5) << endl;
    
    cin.ignore();
    return 0;
}

3.14159
6.28319
73.8274