编程题：Least Prefix
Given a non-empty array of N integers A, please find the smallest integer P such that all the numbers in A are in the subarray A[0..P].
### Input Format:
A positive number N, followed by a list of N non-negative integers less than 1000000. N is no larger than 1000000.
### Output Format:
The smallest integer P.
### Sample Input:
in
6
2 2 1 2 0 1
### Sample Output:
out
4
答案：若无答案欢迎评论
### Input Format:
A positive number N, followed by a list of N non-negative integers less than 1000000. N is no larger than 1000000.
### Output Format:
The smallest integer P.
### Sample Input:
in
6
2 2 1 2 0 1
### Sample Output:
out
4
答案：若无答案欢迎评论
