func_code_string: #include <bits/stdc++.h>   #pragma GCC optimize( Ofast , 3,  inline )   using namespace std;   string s, t;   int n;   void pairr() {     if (cin >> t) {       s += t;       if (t ==  pair ) s +=  < , pairr(), s +=  , , pairr(), s +=  > ;     } else {       cout <<  Error occurred ;       exit(0);     }   }   int main() {     ios_base::sync_with_stdio(false);     cin.tie(0);     cin >> n;     pairr();     if (cin >> t) {       cout <<  Error occurred ;       return 0;     }     cout << s;     return 0;   }   