!-----  Ex7_5: Counting A, B, C ,...   -----
      CHARACTER :: abc*53, input*80
      INTEGER :: freq(0:27) = 0, code(255) = 0,  i, ichi
      LOGICAL :: mask(0:27)
      abc=" ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
!-----   Make a Code Table
      DO ichi = 1, 53
         IF(ichi <= 27) THEN
            code( ICHAR( abc(ichi:ichi) ) ) = ichi
         ELSE
            code( ICHAR( abc(ichi:ichi) ) ) = ichi-26
         END IF
      END DO
!-----   Sentence Input and Count Frequency of each Characters
      DO
          PRINT*, "Write a sentence shorter than 80 characters:"
          READ '(A)', input;    IF( input == "" )  EXIT
          DO i = 1, LEN_TRIM(input)
               ichi = code( ICHAR( input(i:i) ) )
               freq(ichi) = freq(ichi) + 1
          END DO
      END DO
!-----   Array Sorting with use of Mask
      freq(0) = 0; mask = ( freq > 0 )
      DO WHILE( COUNT(mask) > 0 )
           ichi = SUM( MAXLOC(freq, mask))-1
           PRINT '(4X, A1, ":", I5)', abc(ichi:ichi), freq(ichi)
           mask(ichi) = .FALSE.
      END DO
           PRINT '("Total=",I5)', SUM( freq )
      END