#include <bits/stdc++.h>
using namespace std;

int main() {  
  string s;
  cin >> s;
  int n = s.size();
  int win = 0;
  for(int i = 0; i < n; i++) {
    if(s[i]=='o') win++;
  }
  cout << ( win+(15-n)>=8 ?"YES" :"NO") << "\n";
}