#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
int main(){
  string s;
  cin>>s;
  int i,count=0,n=s.size();
  for(i=0;i<n;i++){
	if(s[i]=='x'){
		count++;
    }
  }
  
  cout<<(count<8?"YES":"NO")<<endl; 
}
  
  