#P632C. The Smallest String Concatenation
The Smallest String Concatenation
Description
You're given a list of n strings a1, a2, ..., an. 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.
The first line contains integer n — the number of strings (1 ≤ n ≤ 5·104).
Each of the next n lines contains one string ai (1 ≤ |ai| ≤ 50) consisting of only lowercase English letters. The sum of string lengths will not exceed 5·104.
Print the only string a — the lexicographically smallest string concatenation.
Input
The first line contains integer n — the number of strings (1 ≤ n ≤ 5·104).
Each of the next n lines contains one string ai (1 ≤ |ai| ≤ 50) consisting of only lowercase English letters. The sum of string lengths will not exceed 5·104.
Output
Print the only string a — the lexicographically smallest string concatenation.
Samples
4
abba
abacaba
bcd
er
abacabaabbabcder
5
x
xx
xxa
xxaa
xxaaa
xxaaaxxaaxxaxxx
3
c
cb
cba
cbacbc