Suffixes of one row

You are given a collection of strings: s[1], s[2], ..., s[n].

Your task is to find a string t such that at least one of the given strings is a suffix of t.

Input

The first line contains an integer n (1 ≤ n ≤ 10^5), representing the number of strings in the collection. Each of the next n lines contains one string, where the i-th line contains the non-empty string s[i].

All strings are composed solely of lowercase Latin letters. The combined length of all strings does not exceed 10^5.

Output

If such a string t exists, print it. If there are multiple possible strings t, print the one with the shortest length.

If no such string t can be found, print -1.

Examples