#include<stdio.h>
#include<math.h>
int main()
{
	double a, b, c;
	scanf("%lf %lf %lf", &a, &b, &c);
	double s = (a + b + c) / 2;
	double S = sqrt(s * (s - a) * (s - b) * (s - c));
	double r = 2 * S / (a + b + c);
	printf("%.20lf\n", r);
	return 0;
}