! rearrange characters of a word
PROGRAM ex7_2

  IMPLICIT NONE
  INTEGER :: i, j, k, n = 1
  CHARACTER(LEN=4) :: w0, w1, w2, w(1:24)

  PRINT '(1X, A)', 'Input a word in 4 letters: '
  READ '(A)', w0

  DO i = 1, 4
    w1 = w0(i:i)//w0(1:i-1)//w0(i+1:4)
    DO j = 2, 4
      w2 = w1(1:1)//w1(j:j)//w1(2:j-1)//w1(j+1:4)
      DO k = 3, 4
        w(n) = w2(1:2)//w2(k:k)//w2(3:k-1)//w2(k+1:4)
        n = n + 1
      END DO
    END DO
  END DO

  PRINT '(/(12A5))', w

END PROGRAM ex7_2