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






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