#include <bits/stdc++.h>
using namespace std;
int main(void) {
  long long i, j, k, ss, count;
  string s;
  cin >> s;
  ss = s.size();
  vector<long long> num(26, 0);
  for (i = 0; i < ss; i++) {
    num[s[i] - 'a']++;
  }
  for (i = 0; i < 26; i++) {
    if (num[i] % 2 != 0) count++;
  }
  if (count <= 1) {
    cout << 1 << endl;
    return 0;
  }
  count = 0;
  for (i = 0; i < ss; i++) {
    if (num[s[i] - 'a'] % 2 == 1) {
      count++;
    }
    num[s[i] - 'a']--;
  }
  return 0;
}
