#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(0);
  string s;
  cin >> s;
  int A[3] = {0, 0, 0}, i;
  for (i = 0; i < s.size(); ++i) ++A[s[i] - 'a'];
  sort(A, A + 3);
  cout << (A[2] <= A[0] + A[1] ? "YES" : "NO") << endl;
  return 0;
}
