#include<bits/stdc++.h>
using namespace std;
string s;
int acnt=0,bcnt=0,ccnt=0;
int main(){
	cin>>s;
	for(int i=0;i<s.size();i++){
		if((s[i]=='a'&&s[i]=='c')||(s[i]=='b'&&s[i]=='a')||(s[i]=='c'&&s[i]=='a')||(s[i]=='c'&&s[i]=='b')){
			cout<<"NO";
			return 0;
		}
	}
	if(ccnt==acnt||ccnt==bcnt){
		cout<<"YES";
	}
	return 0;
}