#include <iostream>
#include <cstdio>
#include <cmath>
#include <algorithm>
#include <cstring>
using namespace std;
string s;
double lx=0,rx=0,n,m,l,r;
char c;
int main()
{
    cin>>s;
    n=s.size();
    for(int i=0;i<=n;i++)
        if(s[i]=='=')m=i;
    int x=0;
    while(x<m){
        int f=1,z=0;
        if(s[x]=='-')
        f=-1;
        if(!isdigit(s[x]))x++;
        while(isdigit(s[x]))z=z*10+s[x]-'0',x++;
        if(s[x]>='a'&&s[x]<='z')lx+=f*z,c=s[x];
        else l+=f*z;

    }
    while(x<n){
        int f=1,z=0;
        if(s[x]=='-')
        f=-1;
        if(!isdigit(s[x]))x++;
        while(isdigit(s[x]))z=z*10+s[x]-'0',x++;
        if(s[x]>='a'&&s[x]<='z')rx+=f*z;
        else r+=f*z;

    }
    cout << c << "=";
    printf("%.3lf",(r-l)/(lx-rx));
 	return 0;//orz
}