#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= 0;
    int b = 0;
    int c= 0;
    double sum = 0.0;
    scanf("%d%d%d",&a,&b,&c);
    int ret1 = max3(a+b,b,c);
    int ret2 = max3(a,b+c,c);
    int ret3 = max3(a,b,b+c);
    sum = ret1*1.0/(ret2+ret3);
    printf("%.2lf",sum);
    return 0;
}