Jordan picked 54 mangoes from his tree. One-third of the mangoes were ripe while the other two-thirds were not yet ripe. Jordan kept 16 unripe mangoes and gave the remainder to his sister who pickled them in glass jars. If it takes 4 mangoes to fill a jar, how many jars of pickled mangoes can Jordan's sister make?
Please reason step by step, and put your final answer within \boxed{}.
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