#include <bits/stdc++.h>
using namespace std;
int c[200000][26];
int dp[200000];
int t[26];
int check() {
  int cc = 0;
  for (int i = 0; i < 26; i++) cc += t[i] % 2;
  return cc;
}
int main() {
  string s;
  cin >> s;
  for (int i = 0; i < s.size(); i++) {
    c[i][s[i] - 'a']++;
    dp[i] = 1e9;
  }
  for (int i = 1; i < s.size(); i++) {
    for (int j = 0; j < 26; j++) c[i][j] += c[i - 1][j];
  }
  for (int i = 0; i < s.size(); i++) {
    for (int j = 0; j < 26; j++) t[j] = c[i][j];
    if (check() <= 1) dp[i] = 1;
  }
  for (int i = 0; i < s.size(); i++) {
    if (dp[i] != 1e9)
      for (int j = i + 1; j < s.size(); j++) {
        for (int k = 0; k < 26; k++) t[k] = c[j][k] - c[i][k];
        if (check() <= 1) dp[j] = min(dp[i] + 1, dp[j]);
      }
  }
  cout << dp[s.size() - 1] << endl;
  return 0;
}
