#include<stdio.h>
#include<string.h>
int n;
char a[1048576], ar[1048576];
char buf[1048576];
void rev_str(char *x)
{
	int i, j;
	char tmp;
	for(i=0, j=strlen(x)-1;i<j;i++, j--){tmp=x[i]; x[i]=x[j]; x[j]=tmp;}
}
int main()
{
	int i;
	while(gets(buf))
	{
		for(i=0;buf[i];i++)
		{
			if('A'<=buf[i] && buf[i]<='Z') a[n++]=buf[i]-'A'+'a';
			else if('a'<=buf[i] && buf[i]<='z') a[n++]=buf[i];
		}
	}
	a[n]=0;
	strcpy(ar, a);
	rev_str(ar);
	printf("%s\n", strcmp(a, ar)?"no":"yes");
	return 0;
}