#include <bits/stdc++.h>
using namespace std;
int main() {
  string s;
  cin >> s;
  int i, n, a = 0, b = 0, c = 0;
  n = s.size();
  for (i = 0; i < n; i++) {
    if (s[i] == 'a') {
      a++;
    }
    if (s[i] == 'b') {
      b++;
    }
    if (s[i] == 'c') {
      c++;
    }
  }
  int u = max({a, b, c}), v = min({a, b, c});
  if (u - v <= 1) {
    cout << "YES" << endl;
  }
  cout << "NO" << endl;
}
