func_code_string: #include <bits/stdc++.h>   const long long INF = (long long)1e9 + 9;   const long long maxn = (long long)1e9 + 6;   using namespace std;   signed main() {     long long t;     cin >> t;     while (t--) {       long long n, cnt = 0;       cin >> n;       map<string, long long> mp;       vector<string> s(n), answer(n);       for (long long i = 0; i < n; i++) {         cin >> s[i];         mp[s[i]]++;       }       for (long long i = 0; i < n; i++) {         if (mp[s[i]] == 1) {           answer[i] = s[i];           mp[s[i]] = true;         } else {           string temp = s[i];           mp[temp]--;           cnt++;           for (long long where = 0; where < 4; where++) {             for (char ch =  0 ; ch <=  9 ; ch++) {               temp[where] = ch;               if (not mp.count(temp)) {                 answer[i] = temp;                 mp[temp]++;                 where = 4;                 break;               }             }           }         }       }       cout << cnt << endl;       for (long long i = 0; i < n; i++) {         cout << answer[i] << endl;       }     }     return 0;   }   