You're given four integers, a1,a2,a3,a4, which are the numbers of 1,2,3,4 you have. 这些数只是a1,a2,a3,a4吗？

好好读，认真读每一个词，真坑。

we have a1 1s,a2 2s, a3 3s and a4 4s.