PRINT X
REPEAT 1000 TIMES (
    CLEAR A
    REPEAT X TIMES (
        INCREASE A
    )
    CLEAR B
    REPEAT A TIMES (
        INCREASE B
    )
    REPEAT B TIMES (
        CLEAR C
        INCREASE C
        CLEAR D
        REPEAT C TIMES (
            INCREASE D
        )
    )
)