#include<bits/stdc++.h>
using namespace std;
int main()
{
	int n;
	cin>>n;
	cout<<(!(n%3)?"yes":"no");
}

C++ :

#include <iostream> 
#include <cstdio>
using namespace std;
int main()
{
	int x;
	cin>>x;
	if(x%3 == 0)
	{
		cout<<"yes"<<endl;
	}
	else
	{
		cout<<"no"<<endl;
	}
	return 0;
}