Longest Common Word Prefix

Given a list of strings, each representing a sequence of words separated by spaces, your task is to find the longest common prefix that forms complete words from the beginning of each string.

For example, if the input strings are:

• hello world programming
• hello there
• hello everyone

then the longest common word prefix is hello.

If no non-empty common prefix exists that matches whole words, output an empty string.

Note: The common prefix must match entire words and the matching is performed from the beginning of each string.

You can assume that input strings do not have leading or trailing spaces.

inputFormat

The input is read from stdin and has the following format:

1. An integer n representing the number of strings.
2. Followed by n lines, each line contains a string.

For example:

3
hello world
hello there
hello everyone

outputFormat

The output is written to stdout and should be the longest common prefix (composed of complete words). If there is no common prefix, output an empty line.

## sample

3
hello world
hello there
hello everyone

hello