Problem Statement

Naohiro had N+1 consecutive integers, one of each, but he lost one of them.
The remaining N integers are given in arbitrary order as $A_1,\ldots,A_N.$ Find the lost integer.
The given input guarantees that the lost integer is uniquely determined.

Input

The input is given from Standard Input in the following format:
N
$A_1 A_2 \ldots A_N$

Output

Print the answer.

Constraints

• $2 \leq N \leq 100$
• $1 \leq A_i \leq 1000$
• All input values are integers.
• The lost integer is uniquely determined.

Sample Input 1

3
2 3 5

Sample Output 1

4

Naohiro originally had four integers, 2,3,4,5, then lost 4, and now has 2,3,5.
Print the lost integer, 4.

Sample Input 2

8
3 1 4 5 9 2 6 8

Sample Output 2

7

Sample Input 3

16
152 153 154 147 148 149 158 159 160 155 156 157 144 145 146 150

Sample Output 3

151

见题面 Input 部分

见题面 Output 部分