#include<iostream>
#include<cstdio>
#include<string>
#include<algorithm>
using namespace std;


string S;

int main(){
    cin >> S;
    int cnt[3] = {};
    for(int i = 0; i < S.length(); i++){
        cnt[S[i]-'a']++;
    }
    sort(cnt, cnt+3);
    if(cnt[2]-cnt[0] <= 1){
        cout << "YES" << endl;
    }else{
        cout << "NO" << endl;
    }
}