#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);
}