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

int main(){
   
    string S;cin>>S;
    int m=0;
    for(int i=0;i<S.size();i++){
        if(S[i]=='x') m++;
    }
    if(m<=7) cout<<"YES"<<endl;
    else cout<<"NO"<<endl;
}


