#include <bits/stdc++.h>
using namespace std;
const int inf = 1e9 + 7;
template <class T>
void dbs(string str, T t) {
  cout << str << " : " << t << endl;
}
template <class T, class... second>
void dbs(string str, T t, second... s) {
  int idx = str.find(',');
  cout << str.substr(0, idx) << " : " << t << ",";
  dbs(str.substr(idx + 1), s...);
}
template <class second, class T>
ostream& operator<<(ostream& os, const pair<second, T>& p) {
  return os << "(" << p.first << ", " << p.second << ")";
}
template <class T>
ostream& operator<<(ostream& os, const vector<T>& p) {
  os << "[ ";
  for (auto& it : p) os << it << " ";
  return os << "]";
}
template <class T>
ostream& operator<<(ostream& os, const set<T>& p) {
  os << "[ ";
  for (auto& it : p) os << it << " ";
  return os << "]";
}
template <class second, class T>
ostream& operator<<(ostream& os, const map<second, T>& p) {
  os << "[ ";
  for (auto& it : p) os << it << " ";
  return os << "]";
}
template <class T>
void prc(T a, T b) {
  cout << "[";
  for (T i = a; i != b; ++i) {
    if (i != a) cout << ", ";
    cout << *i;
  }
  cout << "]";
  cout << endl;
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  string s;
  cin >> s;
  int n = s.length();
  vector<int> f(3);
  for (int i = (0); i <= (int(s.size()) - 1); ++i) f[s[i] - 'a']++;
  s = "";
  while (int(s.size()) < n) {
    for (int i = (0); i <= (2); ++i)
      if (f[i]) s += 'a' + i, f[i]--;
  }
  int g = 1;
  for (int i = (1); i <= (n - 1); ++i) {
    g &= s[i] != s[i - 1];
    if (i + 1 < n) g &= (s[i - 1] != s[i + 1]);
  }
  cout << (g ? "YES\n" : "NO\n");
  return 0;
}
