PROGRAM MAIN
    IMPLICIT NONE
    INTEGER :: N

    READ *, N
    IF (MOD(N, 2) == 0) THEN
        PRINT *, 10 ** (N / 2) / 9
    ELSE
        PRINT *, 10 ** (N / 2) / 9 + 6 * 10 ** (N / 2 - 1)
    END IF
END PROGRAM MAIN