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C. INTERCALC

time limit per test

2 secondsmemory limit per test

64 megabytesinput

standard inputoutput

standard outputDO YOU EXPECT ME TO FIND THIS OUT?

WHAT BASE AND/XOR LANGUAGE INCLUDES string?

DON'T BYTE OF MORE THAN YOU CAN CHEW

YOU CAN ONLY DISTORT THE LARGEST OF MATHEMATICS SO FAR

SAYING "ABRACADABRA" WITHOUT A MAGIC AND WON'T DO YOU ANY GOOD

THE LAST STACK RUPTURES. ALL DIE. OH, THE EMBARRASSMENT!

I HAVE NO ARRAY AND I MUST SCREAM

ELEMENTS MAY NOT BE STORED IN WEST HYPERSPACE

Input

The first line of input data contains a single integer *n* (1 ≤ *n* ≤ 10).

The second line of input data contains *n* space-separated integers *a*_{i} (1 ≤ *a*_{i} ≤ 11).

Output

Output a single integer.

Example

Input

4

2 5 3 1

Output

4

Codeforces (c) Copyright 2010-2017 Mike Mirzayanov

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