CHARACTER*70 ASTRING
	CHARACTER*40 INFILE,FILENAME
        character*14 atom1,atom2,atom(100000)
	LOGICAL EFLG
	real*8 M1(3,100000),d(10000)
	INTEGER*4 I,J,k

1200	FORMAT(A)

	WRITE(6,*) 'Find 2 atoms separated by greatest distance'
6	WRITE(6,*) 'ENTER NAME OF pdb file:'
	READ(5,1200) INFILE
	IF (INFILE(:5).EQ.'     ') STOP
	  INQUIRE(FILE=INFILE, NAME=FILENAME,EXIST=EFLG)
	  IF (.NOT.EFLG) GOTO 6
c        OPEN (UNIT=2,FILE=INFILE,STATUS='OLD',READONLY)
        OPEN (UNIT=2,FILE=INFILE,STATUS='OLD')

	k=1
        dmax=-1
        atom1='none'
        atom2='none'
        
c 	read coord         
50	read(2,1200,end=1160) ASTRING
	if ((ASTRING(1:5).ne.'ATOM ').and.(ASTRING(1:6).ne.'HETATM')) 
     .        goto 50
 	read(ASTRING,51) atom(k),(m1(i,k),I=1,3)
C
51 	format (12x,A14,4x,3d8.3,2f6.2)
C compare the atom just read with all previous:        
	do 100 j=1,k-1
	x=0.
	do 90 i=1,3
90	x=x+(m1(i,k)-m1(i,j))**2
c	x=sqrt(x)
	if (x.gt.dmax) then
	dmax=x
        atom1=atom(k)
        atom2=atom(j)
c        write(6,*)k,j,atom1,atom2,sqrt(x)
        endif
100	continue
	k=k+1
	if (k.le.100000)goto 50
	write(6,*)'Processing truncated after first',k-1,' atoms'
1160	CLOSE(UNIT=2)
	k=k-1
	write(6,*)k,' atoms: Max distance is ',atom1,',  ',atom2,sqrt(dmax)
	END