#include <stdio.h>

int max3(int a, int b, int c)
{
    int max = a;
    if (b > max)
        max = b;
    if (c > max)
        max = c;
    return max;
}

int main() 
{
    int a = 0;
    int b = 0;
    int c = 0;
    while (scanf("%d %d %d", &a, &b, &c) == 3)
    {
        float m = 0;
        m = max3(a + b, b, c) * 1.0 /(max3(a, b + c, c) + max3(a, b, b + c));
        printf("%.2f\n", m);
    }
    return 0;
}