Hehe, it's like this. In fact, it can be explained as follows: A said that "at least one person is right". What is the concept of "at least" That is to say, because there are three people besides A who make judgments, the number of people who answer correctly can be one, two or even three, which is the so-called "at least one". Suppose one: "A's stamp is within 1~99", then C and D are correct. Although this fits the meaning of the question, it is not sure how many stamps A has. The question "How many stamps does A have now" is obviously an absolute state of solution, otherwise the question will not be solved. So we can only rule out this assumption. Hypothesis 2: "A has 100 stamps or more". In this case, only B of BCD's three viewpoints is right, that is, one person is right. Because B said "at least 100", it is obviously in line with the hypothesis. Although there is no contradiction with the topic, I still can't determine how many stamps A has, so I can only rule it out. Hypothesis 3: "If A doesn't have any stamps", then C's view of "less than 100 stamps" is correct, and only C is right. In this case, it can not only satisfy the meaning of the question, but also determine the number of seals of A, which is 0! In this question, B and CD are contradictory, but no matter what the contradiction is, because we know that the number of people who are right may be 1~3. If CD is right, we can't be sure that it is 1~ 100. So if there is a solution to this problem, it can only be B, so the only specific number that can be accurately deduced is 0, so the stamp of A is 0! The above is my answer, I hope I can help you. If you don't understand anything, please ask me!