#include <bits/stdc++.h>   using namespace std;   const int N = 100010;   int inf = 1e9;   int mod = 1e9 + 7;   const int M = 20;   signed main() {     ios_base::sync_with_stdio(0);     cin.tie(0);     cout.tie(0);     string s;     cin >> s;     int n = (int)s.length();     int dp[(1 << M)];     memset(dp, 0, sizeof(dp));     int maxi = 0;     for (int i = 0; i < n; i++) {       int mask = 0;       int cnt = 0;       for (int j = i; j < n; j++) {         int x = s[j] -  a ;         if ((mask >> x) & 1) {           break;         }         mask ^= (1 << x);         cnt++;         dp[mask] = cnt;       }       maxi = max(maxi, cnt);     }     for (int i = 0; i < M; i++) {       for (int j = 0; j < (1 << M); j++) {         if (j & (1 << i)) {           dp[j] = max(dp[j], dp[j ^ (1 << i)]);         }       }     }     for (int i = 0; i < (1 << M); i++) {       int comp = (1 << M) - 1 - i;       maxi = max(maxi, dp[i] + dp[comp]);     }     cout << maxi <<   n ;     return 0;   }   