#include <stdio.h>

int max3(int x,int y,int z){
    int max =(((x>y)?x:y)>z)?((x>y)?x:y):z;
    return max;
}

int main() {
    int a = 0;
    int b = 0;
    int c = 0;
    float m = 0;
    scanf("%d %d %d",&a,&b,&c);
    float max1 =max3(a+b,b,c);
    float max2 =max3(a,b+c,c);
    float max4 =max3(a,b,b+c);
    m = max1/(max2+max4);
    printf("%.2f",m);     
    return 0;
}