#include "bits/stdc++.h"
using namespace std;

int main() {
	string S;
	int C[3] = {};
	cin >> S;
	for (int i = 0; i < S.size(); i++) {
		C[S[i] - 97]++;
	}
	sort(C, C + 3);
	if (C[2] - C[0] <= 1) cout << "YES";
	else cout << "NO";
}