Best String

Given a string, you use some letters or digits to creat a new string, this new string have three properties.
1. any two adjacent letter aren't the same.
2. the new string have the biggest length.
3. the new string have the biggest lexicographical ordering.

The input consists of multiple test cases. Each test case contain a string, the string is consist of 'a'~'z', 'A' - 'Z' and '0' - '9'. the length of string is not exceed 500.

For each case, print the new string.

2
abaa
001

aba
010

luzilon1

2010 ACM-ICPC Multi-University Training Contest（7）——Host by HIT