#include <bits/stdc++.h>
int main() {
  std::string S;
  std::cin >> S;
  std::vector<int> count(3);
  count[0] = count[1] = count[2] = 0;
  if (S.size() == 1) {
    std::cout << "YES" << std::endl;
    return 0;
  }
  for (int i = 0; i < S.size(); i++) {
    if (S[i] == 'a') {
      count[0]++;
    } else if (S[i] == 'b') {
      count[1]++;
    } else {
      count[2]++;
    }
  }
  if (count[0] == 0 || count[1] == 0 || count[2] == 0) {
    std::cout << "NO" << std::endl;
    return 0;
  }
  int temp;
  std::sort(count.begin(), count.end());
  if (count[0] == count[1] && count[1] == count[2]) {
    std::cout << "YES" << std::endl;
  } else if (count[0] == count[1] && count[2] == count[0] + 1) {
    std::cout << "YES" << std::endl;
  } else if (count[1] == count[2] && count[0] == count[1] - 1) {
    std::cout << "YES" << std::endl;
  } else {
    std::cout << "NO" << std::endl;
  }
}
