PROGRAM splitA

c	Splits out A monomer from PDB file

	CHARACTER*76 	line
	INTEGER		n/0/

c	Handle files

	WRITE (6, 1000) ' Enter input file name:'
1000	FORMAT (a)
	READ (5, 1000) line
	OPEN (unit=1, file=line, form='FORMATTED', status='OLD')

	WRITE (6, 1000) ' Enter output file name:'
	READ (5, 1000) line
	OPEN (unit=2, form='FORMATTED', status='UNKNOWN', file=line)

	DO WHILE (.TRUE.)
5	  READ (1, 1000, end=9) line
	  IF (line(1:4) .NE. 'ATOM' .AND. line(1:6) .NE. 'HETATM') goto 5
	  IF (line(22:22) .NE. 'A' .AND. line(73:73) .NE. 'A') goto 5
	  line(73:73) = 'A'
	  line(22:22) = ' '
	  n = n + 1
	  WRITE (line(7:11), 1002) n
1002	  FORMAT (i5)
	  WRITE (2, 1000) line
	endDO

9	CLOSE (unit=1)
	CLOSE (unit=2)

	end