B1A4 gave a sweet present to their fans to celebrate their fourth anniversary! �The boys first debuted on April 23, 2011 with "O.K," which they returned to for a special dance practice video.

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Fans get to see the old B1A4 and the first song they released through this video so they can fall in love with the choreography all over again! �The boys are cheerful, energetic, and enthusiastic, suggesting that they've become successful now but it was all thanks to their past.

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