#include <stdio.h>

int Max3(int a, int b, int c)
{
    int max = a > b ? a : b;
    return max > c ? max : c;
}

int main()
{
    int a = 0;
    int b = 0;
    int c = 0;
    scanf("%d %d %d", &a, &b, &c);
    float m = (float)Max3(a + b, b, c) / (Max3(a, b + c, c) + Max3(a, b, b + c));

    printf("%.2f\n", m);

    return 0;
}