func_code_string: #include <bits/stdc++.h>   using namespace std;   long long arr1[26], arr2[26][26];   signed main() {     string s;     cin >> s;     long long n = s.length();     for (long long i = 0; i < n; i++) {       long long ct = s[i] -  a ;       for (long long j = 0; j < 26; j++) {         arr2[j][ct] += arr1[j];       }       arr1[ct]++;     }     long long ans = 0;     for (long long i = 0; i < 26; i++) ans = max(ans, arr1[i]);     for (long long i = 0; i < 26; i++) {       for (long long j = 0; j < 26; j++) {         ans = max(ans, arr2[i][j]);       }     }     cout << ans;   }   