#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.size(); i++) {
    if (s[i] == 'a')
      a++;
    else if (s[i] == 'b')
      b++;
    else
      c++;
  }
  while (a > 0 && b > 0 && c > 0) {
    a--;
    b--;
    c--;
  }
  if ((a == 1 && b == 0 && c == 0) || (a == 1 && b == 1 && c == 0) ||
      (a == 0 && b == 1 && c == 0) || (a == 0 && b == 1 && c == 1) ||
      (a == 0 && b == 0 && c == 1) || (a == 1 && b == 0 && c == 1))
    cout << "YES" << endl;
  else
    cout << "NO" << endl;
  return 0;
}
