#include<stdio.h>
int main()
{
char c,d;
scanf("%c",&c);
if((c<'A')||(c>'z')||(c>'Z'&&c<'a'))
printf("It is not a letter.");
if(c>='A'&&c<='Z')
d='A'+'Z'-c;
if(c>='a'&&c<='z')
d='a'+'z'-c;
printf("%c",d);
return 0;
}