#include <bits/stdc++.h>
using namespace std;
using ll = int;
int main(void) {
  string s;
  cin >> s;
  int a = 0, b = 0, c = 0;
  for (int i = 0; i < s.length(); i++) {
    if (s[i] == a) {
      a++;
    } else if (s[i] == b) {
      b++;
    } else {
      c++;
    }
  }
  if (max(max(abs(a - b), abs(b - c)), abs(c - a)) <= 1) {
    cout << "YES" << endl;
  } else {
    cout << "NO" << endl;
  }
  return 0;
}
