A box contains 100 cards numbered from 1 to 100. A person randomly draws cards from the box. If the difference between at least two cards is 5, then how many cards should the person draw at least.
一个盒子里装有标号为1～100的100张卡片，某人从盒子里随意抽卡片，如果要求取出的卡片中至少有两张标号之差为5，那么此人至少要抽多少张卡片．
<result>51</result>