#include<bits/stdc++.h>
 
using namespace std;
 
 
int main(){
	
  string s;cin >> s;
  int rem = 15 - s.size();
  int won = 0;
  for(auto x:s){
  	if(x == 'o') ++won;
  }
  if(won + rem >= 8) cout << "YES";
  else cout << "NO";
}