INTERCALC

题目描述

DO 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

输入输出格式

输入格式

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 $ ).

输出格式

Output a single integer.

输入输出样例

输入样例 #1

4
2 5 3 1

输出样例 #1

4