func_code_string: #include <bits/stdc++.h>   using namespace std;   ifstream inp( inp.txt );   ofstream out( out.txt );   const int N = 1e5 + 5;   const long long B = 73;   int builtin_popcount(int &mask) {     int kol = 0;     for (int bit = 0; bit < 20; bit++) kol += int(bool(mask & (1 << bit)));     return kol;   }   signed main() {     ios::sync_with_stdio(0);     ios_base::sync_with_stdio(0);     cin.tie(0);     cout.tie(0);     string a;     cin >> a;     int up = (1 << 20);     vector<int> dp(up, 0);     vector<int> masks;     for (int i = 0; i < ((int)a.size()); i++) {       int mask = 0;       for (int j = i; j < min(((int)a.size()), i + 20); j++) {         int bit = a[j] -  a ;         if (mask & (1 << bit)) break;         mask |= (1 << bit);         masks.push_back(mask);         dp[mask] = builtin_popcount(mask);       }     }     for (int mask = 1; mask < up; mask++)       for (int bit = 0; bit < 20; bit++)         if (mask & (1 << bit)) dp[mask] = max(dp[mask], dp[mask ^ (1 << bit)]);     int ans = 0;     for (auto &mask : masks)       ans = max(ans, builtin_popcount(mask) + dp[mask ^ (up - 1)]);     cout << ans;     return 0;   }   