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

int main() {
	char s[100];
	scanf("%s", s + 1); int k = strlen(s + 1);
	int cnt = 15 - k;
	for (int i = 1; i <= k; ++i) cnt += s[i] == 'o';
	puts(cnt >= 8 ? "YES" : "NO");
	return 0;
}