题解在此

#include <iostream>
#include <cstdio>
using namespace std;
int main(){
    double a,b,c;
    cin>>a>>b>>c;
    printf("%.2lf",max(a,max(b,c))/(max(a+b,max(b,c))*max(a,max(b,b+c))));
    return 0;
}