findNumber — Pascal Encryption

Repeatedly build a new array from the sums of adjacent pairs modulo 10 until only two elements remain, then output them as a two-character string; leading 0s must not be dropped.

输入格式

The first line contains n (2..5000), and the second line contains n digits from 0..9.

输出格式

Output a string of exactly two digits, keeping leading 0s.

样例 1

输入：

4
4 5 6 7

输出：

04

样例 2

输入：

2
0 0

输出：

00

样例 3

输入：

3
9 9 9

输出：

88

样例说明

Example 1: 4 5 6 7→9 1 3→0 4, output 04. Example 2: already two digits, output 00 as is. Example 3: 9 9 9→8 8, output 88.