#include<bits/stdc++.h>
using namespace std;
 
int main() {
  int w=0, k=0;
  string s; cin >> s;
  k=s.length();
  for (int i=0; i<k; i++) if(s[i]=='o') w++;
  if(15-k+w>=8) cout << "YES" << "\n";
  else cout << "NO" << "\n";
}