PROGRAM ATCODER

implicit none
character(len=1) :: e

read(*,*) e

if ( e == 'A' ) then
  write(*,'(a)') 'T'
end if

if ( e == 'T' ) then
  write(*,'(a)') 'A'
end if

if ( e == 'C' ) then
  write(*,'(a)') 'G'
end if

if ( e == 'G' ) then
  write(*,'(a)') 'C'
end if


contains
!!!!!! サブルーチンは↓
!!!!!!

END PROGRAM ATCODER
