Xiaoli's father and mother work in different companies. Her father has a rest day every 4 days, and her mother has a rest day every 3 days. On June 1, they rest at the same time, so how many days in June will they rest at the same time next time?
小丽的爸爸、妈妈在不同的公司上班，爸爸每4天中有一个休息日，妈妈每3天中就有一个休息日．6月1日，他们同时休息，那么下一次他们同时休息是6月多少日．
<gadget id="calculator">1 + 12</gadget>
<output>13</output>

<result>13</result>