Question
MEX
You are given a sequence of length N consisting of integers:
A=(A1, A2,...., AN)
Find the smallest non-negative integer not in (A1, A2,....,AN).
A=(A1, A2,...., AN)
Find the smallest non-negative integer not in (A1, A2,....,AN).
Input
The input contains N and elements of sequence separated by a new line.
N
A1, A2,. , AN
Constraints
1≤N≤2000
0≤Ai≤2000
All values in the input are integers.
N
A1, A2,. , AN
Constraints
1≤N≤2000
0≤Ai≤2000
All values in the input are integers.
Output
Print the answer.
Example
Sample Input 1
8
0 3 2 6 2 1 0 0
Sample Output 1
4
Sample Input 2
3
2000 2000 2000
Sample Output 2
0
8
0 3 2 6 2 1 0 0
Sample Output 1
4
Sample Input 2
3
2000 2000 2000
Sample Output 2
0