You've got string s , consisting of only lowercase English letters. Find its lexicographically maximum subsequence. We'll call a non-empty string s[p 1 p 2... p k ] = s p 1 s p 2 ... s p k (1 ≤ p 1 p 2 p k ≤ s) a subsequence of string s = s 1 s 2... s s . String x = x 1 x 2... x x is lexicographically larger than string y = y 1 y 2... y y , if either x y and x 1 = y 1, x 2 = y 2, ... , x y = y y , or exists such number r (r x, r y), that x 1 = y 1, x 2 = y 2, ... , x r = y r and x r + 1 y r + 1 . Characters in lines are compared like their ASCII codes.

输入描述:

The single line contains a non-empty string s, consisting only of lowercase English letters. The string's length doesn't exceed 105.

输出描述:

Print the lexicographically maximum subsequence of string s.

备注:

Let's look at samples and see what the sought subsequences look like (they are marked with uppercase bold letters).The first sample: aBaBBAThe second sample: abbCbCCaCbbCBaaBA