#include<cstdio>
#include<cstring>

char s[111];

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