Code in C++ please:

You're given a list of n strings a₁,a₂,...,a_n. You'd like to concatenate them together in some order such that the resulting string would be lexicographically smallest.

Given the list of strings, output the lexicographically smallest concatenation.

Input

The first line contains integer n the number of strings (1n510⁴).

Each of the next n lines contains one string a_i (1|a_i|50) consisting of only lowercase English letters. The sum of string lengths will not exceed 510⁴.

Output

Print the only string a the lexicographically smallest string concatenation.

Examples

Input

4 abba abacaba bcd er 

Output

abacabaabbabcder 

Input

5 x xx xxa xxaa xxaaa 

Output

xxaaaxxaaxxaxxx 

Input

3 c cb cba 

Output

cbacbc