func_code_string: #include <bits/stdc++.h>   #pragma GCC optimize( O3 )   using namespace std;   const int N = 5e3 + 5;   int n, vis[26][26][N];   string s;   long double ans;   int main() {     ios::sync_with_stdio(0);     cout << fixed << setprecision(12);     cin >> s;     n = s.size();     for (int i = 0; i < n; i++) {       for (int j = 0; j < n; j++) vis[s[0] -  a ][s[j] -  a ][j]++;       s.push_back(s.front());       s.erase(s.begin());     }     for (int i = 0; i < 26; i++) {       int mx = 0;       for (int j = 0; j < n; j++) {         int cnt = 0;         for (int k = 0; k < 26; k++) {           cnt += (vis[i][k][j] == 1);         }         mx = max(mx, cnt);       }       ans += mx;     }     cout << ans / (long double)n;     return 0;   }   