Problem: Shil is your new boss and he likes palindromes very much.  Palindrome is a string that can be read the same way in either direction, from the left to the right and from the right to the left. (ex. madam , aabaa, racecar)  

Given a string S , beautiful Palindrome is a lexicographical minimum palindrome that can be formed by rearranging all the characters of string S. In order to please your boss, find a beautiful Palindrome that can be formed with help of string S.  

String x is lexicographically less than string y, if either x is a prefix of y (and x ≠ y), or there exists such i (1 ≤ i ≤ min(|x|, |y|)), that xi < yi, and for any j (1 ≤ j < i) xj = yj. Here |a| denotes the length of the string a. The lexicographic comparison of strings is implemented by operator < in modern programming languages​​.

Input:
Only line of input contains string S. All the letters of this string will be in lower letters('a' - 'z').

Output:
Output lexicographical minimum Palindrome that can be formed by rearranging all the letters of string S. If no such Palindrome exist for given  input, print -1.

Constraints: 
1≤|S|≤100000

SAMPLE INPUT
aabcc

SAMPLE OUTPUT
acbca

Explanation

After rearranging all the characters , all the palindromes that can be formed are cabac and acbca. Out of these two lexicographical minimum one is acbca.

Solution (in PYTHON):

Solution:
s = raw_input()
s = ''.join(sorted(s))
middle = ""
str_ = ""
i = 0
found = 0
if len(s) == 1:
	print "%s"%s
	exit(0)
while(i < len(s)):
	if (i+1) < len(s) and s[i] != s[i+1]:
		middle = s[i]
		i += 1
		if found == 0:found = 1
		else:
			found = 2
			break
	else:
		str_ += s[i]
		i +=2
if found == 2: print "-1"
else:print "%s%s%s" % (str_, middle, str_[::-1])