#include <iostream>
#include <string>
using namespace std;

int main() {
	string S;
	cin >> S;
	int a = 0;
	for (char& i : S) {
		if (i == 'o') ++a;
	}
	if (a - S.size() + 15 < 8) cout << "NO";
	else cout << "YES";
}