/*
codr: timiter
task: abcd
lang: C++
*/

#include <cstdio>

using namespace std;

double p, q, r;

int main()
{
    scanf("%lf %lf %lf", &p, &q, &r);

    if (p == r)
    {
        printf("%.4lf\n", 2 * p * (p + q));
    }
    else
    {
        printf("0\n");
    }

    return 0;
}
