uva problem 10286 Trouble with a Pentagon solution

#include<bits/stdc++.h>
#define x 1.0673956817111818692592637626711
using namespace std;
int main()
{
    double a;
    while(scanf("%lf", &a)!=EOF){
        printf("%0.10lf\n",a*x);
    }

    return 0;
}