#include <bits/stdc++.h>

using namespace std;

int main(){
    string a, b, r = "";
    cin >> a >>  b;

    if(b.size()>a.size()){
        int j= a.size()-1;
        for(int i=b.size()-1; i>=0; i--){
            if(j!=-1){
                if((((b[i]-'0') >= 7) and ((a[j]-'0') >=7)) or (((b[i]-'0') <= 2) and ((a[j]-'0') <=2))){
                    r = '0'+r;
                } else{
                    r = '9'+r;
                }
                j--;
            } else {
                a = '0' + a;
                j=0;
                if((((b[i]-'0') >= 7) and ((a[j]-'0') >=7)) or (((b[i]-'0') <= 2) and ((a[j]-'0') <=2))){
                    r = '0'+r;
                } else{
                    r = '9'+r;
                }
            }
        }

    } else{
        int j= b.size()-1;
        for(int i=a.size()-1; i>=0; i--){
            if(j!=-1){
                if((((a[i]-'0') >= 7) and ((b[j]-'0') >=7)) or (((a[i]-'0') <= 2) and ((b[j]-'0') <=2))){
                    r = '0'+r;
                } else{
                    r = '9'+r;
                }
                j--;
            } else {
                b = '0' + b;
                j=0;
                if((((a[i]-'0') >= 7) and ((b[j]-'0') >=7)) or (((a[i]-'0') <= 2) and ((b[j]-'0') <=2))){
                    r = '0'+r;
                } else{
                    r = '9'+r;
                }
            }
        }
    }

            cout << r << endl;

}