import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.IntSummaryStatistics;
import java.util.Iterator;
import java.util.PrimitiveIterator;
import java.util.Scanner;
import java.util.stream.IntStream;
import java.util.stream.Stream;

class Main{
	private void solve(){
		int[] v=new int[3];
		s.next().chars().map(i->i-'a').forEach(i->++v[i]);
		IntSummaryStatistics iss=Arrays.stream(v).summaryStatistics();
		System.out.println(iss.getMax()-iss.getMin()<2?"YES":"NO");
	}

	public static void main(String[] $){
		new Main().solve();
		System.out.flush();
	}


	static class System{
		private static final InputStream	in	=java.lang.System.in;
		private static final PrintWriter	out	=new PrintWriter(java.lang.System.out,false);
	}

	static Scanner s=new Scanner(System.in);


	static int gInt(){
		return s.nextInt();
	}

	static long gLong(){
		return s.nextLong();
	}

	static long gDouble(){
		return s.nextLong();
	}


	static Range rep(int i){
		return new Range(i);
	}

	static Range rep(int f,int t){
		return new Range(f,t);
	}

	static class Range implements Iterable<Integer>,PrimitiveIterator.OfInt{
		int from,to,c;
		Range(int from,int to){
			this.from=from;
			this.to=to;
			this.c=from;
		}
		Range(int n){
			this(0,n-1);
		}
		@Override
		public Iterator<Integer> iterator(){
			return this;
		}
		@Override
		public boolean hasNext(){
			return c<=to;
		}
		@Override
		public int nextInt(){
			return c++;
		}
	}


	static IntStream REPS(int v){
		return IntStream.range(0,v);
	}

	static IntStream REPS(int l,int r){
		return IntStream.rangeClosed(l,r);
	}


	static IntStream ints(int n){
		return REPS(n).map(i->gInt());
	}

	static Stream<String> strs(int n){
		return REPS(n).mapToObj(i->s.next());
	}

}