#include<iostream>

using namespace std;
int main()
{
int sum=0;
string s;
while(cin>>s)
{
if(s[0]=='-')
s[0]=0;
for(int i=0;i<s.size();i++)
{
sum+=s[i]%3;
}
if(sum%3==0)
cout<<"yes"<<endl;
else
cout<<"no"<<endl;
sum=0;
}

return 0;
}