func_code_string: #include <bits/stdc++.h>   using namespace std;   void debugv(std::vector<long long> v);   void printv(std::vector<long long> v);   void inputv(std::vector<long long> &v);   void solve() {     long long n;     cin >> n;     string s;     cin >> s;     unordered_map<string, long long> mp;     for (long long i = 0; i < n - 1; i++) {       string k = s.substr(i, 2);       mp[k]++;     }     long long maxi = INT_MIN;     string ans =   ;     for (auto i : mp) {       if (i.second > maxi) {         ans = i.first;         maxi = i.second;       }     }     cout << ans;   }   int main() {     ios_base::sync_with_stdio(false);     cin.tie(NULL);     long long t;     t = 1;     while (t--) {       solve();       cout <<   n ;     }     return 0;   }   void debugv(std::vector<long long> v) {     long long size = v.size();     for (long long i = 0; i < size; i++) {       cerr << v[i] <<    ;     }     cout <<   n ;   }   void printv(std::vector<long long> v) {     long long size = v.size();     for (long long i = 0; i < size; i++) {       cout << v[i] <<    ;     }     cout <<   n ;   }   void inputv(std::vector<long long> &v) {     for (auto &i : v) {       cin >> i;     }   }   