#include <cstdio>

int main(void) {
  double a, b, c;
  scanf("%lf%lf%lf", &a,&b,&c);
  if ( a != c ) {
    printf("0\n");
    return 0;
  }
  
  printf("%.4lf\n", 2 * a * (a + b));
  return 0;
}
