#include <bits/stdc++.h>
using namespace std;
int main(void) {
  string s;
  cin >> s;
  int t[3];
  for (int i = 0; i < s.size(); i++) {
    t[s[i] - 'a']++;
  }
  int a = min({t[0], t[1], t[2]});
  t[0] -= a, t[1] -= a, t[2] -= a;
  if (t[0] <= 1 && t[1] <= 1 && t[2] <= 1)
    cout << "YES" << endl;
  else
    cout << "NO" << endl;
}
