#include<stdio.h>
#include<string.h>
char in[501][10000];
char in1[10000];
int count = 0, have_it_ever_been;
int main() {


	while (gets(in1)) {
		have_it_ever_been =0;
		for (int i = 0; in1[i] != '\0'; i++)
			in[count][i] = in1[i];


		for(int i=0;i<count;i++)
			if (strstr(in[i], in1)&& strstr(in1, in[i])) 
			{
				have_it_ever_been = 1;
				break;
			}
		

		if (have_it_ever_been == 0)
			printf("NO\n");
		else
			printf("YES\n");
		count++;
		have_it_ever_been = 0;
	}

}