#include <iostream>
#include <math.h>

#define eps 1e-10

using namespace std;

double p, q, r;

int main () {
  //freopen ("test.in", "r", stdin);
  //freopen ("test.out", "w", stdout);

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

  if (fabs (p - r) > eps) {
    printf ("0\n");
    return 0;
  }

  printf ("%.4lf\n", p*(p + q)*2.0);
}