#include <bits/stdc++.h>
using namespace std;
int main() {
  string S;
  cin >> S;
  int a = 0, b = 0, c = 0;
  for (int i = 0; i < S.length(); i++) {
    if (S[i] == 'a')
      a += 1;
    else if (S[i] == 'b')
      b += 1;
    else if (S[i] == 'c')
      c += 1;
  }
  if ((a - b) * (a - c) == 0 || (a - b) * (a - c) == 1)
    cout << "YES";
  else
    cout << "NO";
}
