Problem Statement

We have 4 cards with an integer 1 written on it, 4 cards with $2, \ldots, 4$ cards with N, for a total of 4N cards.
Takahashi shuffled these cards, removed one of them, and gave you a pile of the remaining 4N-1 cards. The $i-th card (1 \leq i \leq 4N - 1)$ of the pile has an integer A_i written on it.
Find the integer written on the card removed by Takahashi.

Input

Input is given from Standard Input in the following format:
N
$A_1 A_2 \ldots A_{4N - 1}$

Output

Print the answer.

Constraints

• $1 \leq N \leq 10^5$
• $1 \leq A_i \leq N$ $, (1 \leq i \leq 4N - 1)$
• For each k $, (1 \leq k \leq N),$ there are at most 4 indices i such that A_i = k.
• All values in input are integers.

Sample Input 1

3
1 3 2 3 3 2 2 1 1 1 2

Sample Output 1

3

Takahashi removed a card with 3 written on it.

Sample Input 2

1
1 1 1

Sample Output 2

1

Sample Input 3

4
3 2 1 1 2 4 4 4 4 3 1 3 2 1 3

Sample Output 3

2

见题面 Input 部分

见题面 Output 部分