#include<stdio.h>
int main()
{
    char A;
    while((A=getchar())!=EOF)
    {
        getchar();
        if(A>='A'&&A<='Z')
        {
            printf("YES\n");
        }
        else if(A>='a'&&A<='z')
        {
            printf("YES\n");
        }
        else
        {
            printf("NO\n");
        }
    }
    return 0;
}