#include <stdio.h>
#include <math.h>
#define ABS(x) (((x)<0)?(-(x)):((x)))

void main()
{
	float m1,m2,a,x,y,c;
	double h1,h2,c1;
	while(scanf("%f",&x)==1)
	{
		if(scanf("%f",&y)!=1)break;
		if(scanf("%f",&c)!=1)break;
		m1=0;
		m2=(x<y)?(x):(y);
		
		while(1)
		{
			a=(m2+m1)/2;
			h1=sqrt(x*x-a*a);
			h2=sqrt(y*y-a*a);
			c1=(h1*h2)/(h1+h2);
			if(ABS(c1-c)<0.001)break;
				else if(c<c1)m1=a;
					else m2=a;

		}
		printf("%.3f\n",a);
	}
}