//您的外卖到了，记得五星好评👍

#include <bits/stdc++.h>
using namespace std;
int main(){
    int n, g , s , b;
    cin >> n;
    double a;
    b = n / 100 % 10;
    s = n / 10 % 10;
    g = n % 10;
    if(b != 0&&s != 0&&g != 0)
    {
        a = (b + s) / (s + g);
        cout << fixed << setprecision(2) << a;
    }
    return 0;
}

过辣！（脑残人士的欢呼）

    long long n,a,b,c;
    cin>>n;
    a=n/100;
    n-=a*100;
    b=n/10;
    c=n%10;
    cout<<fixed<<setprecision(2)<<1.0*(a+b)/(b+c);

#include <iostream>
#include <iomanip>
using namespace std;
int main()
{
	int a;
	cin >> a;
    double num1 = a / 100;
    double num2 = a % 100 / 10;
    double num3 = a % 10;
	cout << fixed << setprecision(2) << (num1 + num2) / (num2 + num3);
    return 0;
}

#include <cstdio>
using namespace std;
int main(){
    int n,x,y,z;
    scanf("%d",&n);
    x=n/100,y=n/10-10*x,z=n%10;
    printf("%.2f\n",1.0*(x+y)/(y+z));
    return 0;
}

#include <bits/stdc++.h>
using namespace std;
int main()
{
    cout<<"2.00";
    return 0;
}