#include<stdio.h>
#include<math.h>
int max(int a, int b, int c);
int main() {
    int a, b, c;
    scanf("%d%d%d", &a, &b, &c);
   double k1,k2,k3;
   k1 = max(a+b,b,c);
   k2 = max(a,b+c,c);
   k3  = max(a,b,b+c);
   double sum = (k1*1.0)/(k2+k3);
    printf("%.2lf", sum);
    return 0;
}
int max(int a, int b, int c) {
    int max = a>b?a:b;
    if(max>c)
    return max;
    else 
    return c;
}