#include<stdio.h>
int max3(int a, int b, int c)
{
int max = a;
if(max < b)
max = b;
if(max < c)
max = c;
return max;
}
int main()
{
int a, b, c;
scanf("%d %d %d", &a, &b, &c);
int x = max3(a+b, b, c);
int y = max3(a, b+c, c);
int z = max3(a, b, b+c);
float m = (float) x / (y + z);
printf("%.2f", m);
}