#include<bits/stdc++.h>
using namespace std;
int main()
{
    string s;
    int ans=0;
    cin>>s;
    for(int i=0;i<s.size();i++) if(s[i]=='x') ans++;
    if(ans<8)cout<<"YES"<<endl;
    else cout<<"NO"<<endl;
    return 0;
}