CODE:

#include <bits/stdc++.h>
using namespace std;

char keys[130];
bool flag[130];
int main(){
    for (int i = 0; i < 130; i ++){
        keys[i] = '@';
    }
    
    string a, b, c;
    cin >> a >> b >> c;
    
    for (int i = 0; i < a.length(); i ++){
        if (keys[a[i]] != '@' && keys[a[i]] != b[i]){
            cout << "Failed";
            return 0;
        }else{
            keys[a[i]] = b[i];
        }
    }
    
    for (int i = 0; i < a.length(); i ++){
        flag[a[i]] = 1;
    }
    
    string ans = "";
    for (int i = 0; i < c.length(); i ++){
        if (keys[c[i]] == '@' || !flag[c[i]]){
            cout << "Failed";
            return 0;
        }else{
            ans += keys[c[i]];
        }
    }
    cout << ans;
}

RECORD:link

WA on #1,#4