func_code_string: #include <bits/stdc++.h>   using namespace std;   const int INF = INT_MAX;   const signed long long int LINF = LLONG_MAX;   const double EPS = 1e-9;   const int MOD = 1000000007;   const int MAXN = 100001;   const int ALPH = 26;   const int DALPH = 52;   int q;   map<string, string> match, rmatch;   set<string> current;   int main() {     scanf( %d , &q);     while (q--) {       string s1, s2;       cin >> s1 >> s2;       if (current.find(s1) == current.end()) {         current.insert(s2);         match[s1] = s2;         rmatch[s2] = s1;       } else {         current.erase(s1);         current.insert(s2);         match[rmatch[s1]] = s2;         rmatch[s2] = rmatch[s1];         rmatch.erase(s1);       }     }     printf( %d n , (int)(match).size());     for (pair<string, string> p : match) {       cout << p.first <<     << p.second <<   n ;     }   }   