#include <stdio.h>
int main()
{
  unsigned char MAC_controller[8] = {0},*m=MAC_controller;
  if( 6==scanf("%02hhx%02hhx%02hhx%02hhx%02hhx%02hhx",m,m+1,m+2,m+3,m+4,m+5) )
    puts("OK"),printf("%llx",*(unsigned long long*)m);
}