character line*120,coded*120,lkey*26
        integer key(26),ikey(26),ncase(26)
        do 49 i=1,120
          coded(i:i)=' '
          line(i:i)=' '
  49    continue
        do 53 i=1,26
          ncase(i)=0
  53    continue

        write (*,*)'This programme reads the key from the'
     &     //' file MonoAlph.key'
        open(8,file='MonoAlph.key',form='formatted')
        read(8,*)lkey
        do 46 i=1,26
          nl=ichar(lkey(i:i))
          if(nl.ge.97)then
            nl=nl-32
            ncase(i)=1
          end if
c         write(*,*)"*** ",i,nl,nl-64,ncase(i)
          key(i)=nl
  46    continue

  48    write(*,*)'Do you want to (1) encode or (2) decode?'
        read(*,*)icode
        if(icode.ne.1.and.icode.ne.2)go to 48
        if(icode.eq.2)then
          do 47 i=1,26
            ikey(key(i)-64)=i+64
c           write(*,*)ncase(i),lkey(i:i),key(i),ikey(i)
  47      continue
        end if

  45    write(*,*)'Do you want (1) UPPER CASE or (2) lower case'
     &   //' or (3) mixed according to the key for encoding?'
        read(*,*)icase
        if(icase.lt.1.or.icase.gt.3)go to 45
       
        open(8,file="MonoAlph.txt",form="formatted")
  1     read(8,1000,end=2)line
1000    format(a120)
        do 15 i=1,120
          nl=ichar(line(i:i))
          if(nl.ge.97.and.nl.le.122)then
            nl=nl-32
          end if
          nlo = nl
          if(nl.ge.65.and.nl.le.90)then
            if(icode.eq.1)nlo=key(nl-64)
            if(icode.eq.2)nlo=ikey(nl-64)
            if(icase.eq.2)nlo=nl+32
            if(icase.eq.3.and.icode.eq.1)nlo=nlo+32*ncase(nl-64)
          end if
          if(nl.lt.32)nlo=32
          coded(i:i)=char(nlo)
  15    continue
        write(*,1000)coded
        go to 1

  2     close(8)

        stop
        end