You took the tile someone was adding to a pung.
A player promoted a pung to a kong, and that fourth tile was the one you were waiting for. You take it out of their hand before the kong completes.
A concealed kong can normally not be robbed at all. The one exception is a Thirteen Orphans hand, which may.
Play Mahjong Winds
Every win shows its faan line by line, using the table on this page.
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