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:
from collections import Counter
s=raw_input()
c=Counter(s)
ch=''

if len(s)%2==0:
	for k,v in c.most_common(1000):
		if v%2!=0:
			print "-1"
			exit()
else:

	cnt=0
	for k,v in c.most_common(1000):
		if v%2!=0:
			cnt+=1
			ch=k

	if cnt!=1:
		print "-1"
		exit()
		
	
c=sorted(c.items())
ans=""
for item in c:
	ans+=item[0]*(item[1]/2)
	
if len(s)%2!=0:
	x=ans
	ans+=ch
	ans+=x[::-1]
else:
	ans+=ans[::-1]

print ans