CF909A.Generate Login

The preferred way to generate user login in Polygon is to concatenate a prefix of the user's first name and a prefix of their last name, in that order. Each prefix must be non-empty, and any of the prefixes can be the full name. Typically there are multiple possible logins for each person.

You are given the first and the last name of a user. Return the alphabetically earliest login they can get (regardless of other potential Polygon users).

As a reminder, a prefix of a string $s$ is its substring which occurs at the beginning of $s$ : "a", "ab", "abc" etc. are prefixes of string "{abcdef}" but "b" and 'bc" are not. A string $a$ is alphabetically earlier than a string $b$ , if $a$ is a prefix of $b$ , or $a$ and $b$ coincide up to some position, and then $a$ has a letter that is alphabetically earlier than the corresponding letter in $b$ : "a" and "ab" are alphabetically earlier than "ac" but "b" and "ba" are alphabetically later than "ac".

The input consists of a single line containing two space-separated strings: the first and the last names. Each character of each string is a lowercase English letter. The length of each string is between 1 and 10, inclusive.

Output a single string — alphabetically earliest possible login formed from these names. The output should be given in lowercase as well.