#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;
}