!-----  Ex6_8: Eratosthenes Sieve (with use of Array Functions)  -----
      INTEGER, ALLOCATABLE :: index(:)
      INTEGER :: lim = 0, n
      DO WHILE( lim <= 1 ) 
            PRINT*, 'Upper limit?';  READ*, lim
      END DO
      ALLOCATE( index(lim) )
      index = (/ 0, (n, n= 2, lim) /)
      DO n = 2, INT( lim**0.5 )
           IF( index(n) == 0 ) CYCLE
           index( n**2 : lim : n ) = 0
      END DO
      PRINT '(I5, A)', COUNT(index/=0), " prime numbers are found."
      PRINT '(10I6)', PACK( index, index/=0 )
      END