#include <iostream>
#include <cmath>

using namespace std;

string s;

int main () {
	cin>>s;
	int br=0;
	for(int i=0;i<s.length();i++){
		if(s[i]=='x') br++;
	}
	if(br>=8) cout<<"NO";
	else cout<<"YES";


return 0;
}

