Common Suffix

Mr. Wang is a freshman majoring in computer science. The teahcer asks him to find the

longest common suffix string amongst an array of strings. Can you help him to solve it?

Input

The input consists of multiple tests. For each test:

Line 1: A number n indicates the number of strings. (\(1 \leq N \leq 1000\))

Line 2: n character strings separated by space.(each string: \(1 \leq length \leq 10000\))

Tests end when n=0.

Output

For each case, print out the longest common suffix string. If not exists, print out None.

Sample Input

2
welcome scuhome
5
software computer helloer worlder finder
1
lastone
0

Sample Output

ome
None
lastone

Author

imcmy