Competitions

# XOR Contest

# Lost card

For the board game the deck of cards is used with numbers from **1** to **n** (positive integer **n** does not exceed `10`

). One card is lost. Find it.^{6}

#### Input

The first number is **n**. Then goes **n - 1** numbers of left cards.

#### Output

Print the number of lost card.

Input example #1

5 1 2 3 4

Output example #1

5

Input example #2

4 3 2 4

Output example #2

1