#include<bits/stdc++.h>
using namespace std;
char s[100007];
int a,b,c;
int main()
{
	scanf("%s",s);
	int len=strlen(s);
	for (int i=0;i<len;i++)
	{
		if (s[i]=='a') ++a;
		if (s[i]=='b') ++b;
		if (s[i]=='c') ++c;
	}
	if (abs(a-b)<=1&&abs(b-c)<=1&&abs(c-a)<=1) cout << "YES" << endl;
	else cout << "NO" << endl;
	return 0;
}