#include <math.h>
#include <stdio.h>

int main(void) {
  // Initialize values
  int a, b, c;
  scanf("%i %i %i", &a, &b, &c);

  // Calculate S and area's 2 power
  double s = (a + b + c) / (double)2;
  double area = (s * (s - a) * (s - b) * (s - c));

  // Print answer
  (area > 0) ? printf("%.3lf", sqrt(area))
             : printf("The edges cannot make up of a triangle.");

  return 0;
}