#include <iostream>
#include <string>
using namespace std;
int main()
{
	string ch;
	cin >> ch;
	int kq=0;
	for(int i=0; i<ch.size(); i++)
	{
		if(ch[i]=='o') kq++;
	}
	cout << (kq+(15-ch.size())>=8?"YES":"NO");
}