#include <bits/stdc++.h>
using namespace std;
string s;
int cou[3];
int main() {
  cin >> s;
  for (int i = (0); i <= (2); i++) {
    for (int c : s) {
      if (c == 'a' + i) cou[i]++;
    }
  }
  if (!((cou[0] % 2) + (cou[1] % 2) + (cou[2] % 2) <= 1)) {
    cout << "YES" << endl;
    return 0;
  }
  if (cou[0] == 0 || cou[1] == 0 || cou[2] == 0) {
    cout << "NO" << endl;
    return 0;
  } else {
    cout << "YES" << endl;
  }
}
