The Smallest String Concatenation

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.

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.

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

inputFormat

outputFormat

output the lexicographically smallest 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.

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

样例

4
abba
abacaba
bcd
er

abacabaabbabcder

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