program security
implicit none
character::S*4
integer::i,check
read(*,*)S
check=0
do i=1,3
	if(S(i:i)==S(i+1:i+1))then
    	check=check+1
    else
    	check=check
    end if
end do
if(check==0)then
write(*,*)'Good'
else
write(*,*)'Bad'
end if
end program security