short 思考题

A^B Problem

Given two pattern strings A and B that consists of lower-case letters, ? (match a single character) and * (match one or more characters)

For example, abc?d*e matches abcfdppe and abcgde but not ae or abcdde.

Find a string that matches A but not B or output IMPOSSIBLE.

Example

A='abc???e'
B='abc*fe'

Out: abcggge

A='abc???e'
B='a*'
Out: IMPOSSIBLE