#include<bits/stdc++.h>
using namespace std ;
int main(){
    string s ;
    int a , b , c ;
    a = b = c = 0 ;
    cin >> s ;
    int len = s.length() ;
    for( int i = 0 ; i < len ; i++ ){
        if ( s[i] == 'a' ) a++ ;
        if ( s[i] == 'b' ) b++ ;
        if ( s[i] == 'c' ) c++ ;
    }
    int maxx = max( max( a , b ) , c ) ;
    int minx = min( min( a , b ) , c ) ;
    if ( maxx - minx > 1 ) cout << "NO" << endl ;
    else cout << "YES" << endl ;
    return 0 ;
}