#include <bits/stdc++.h>
using namespace std;
int main() {
  string s;
  cin >> s;
  int abc[3];
  fill(abc, abc + 3, 0);
  for (int i = 0; i < s.length(); ++i) ++abc[s[i] - 'a'];
  int M = max({abc[0], abc[1], abc[2]}), m = min({abc[0], abc[1], abc[2]});
  if (M < m + 2)
    cout << "YES" << endl;
  else
    cout << "NO" << endl;
  return 0;
}
