Furloughs are hitting government workers this year. To commemorate getting one unpaid day off each week until the end of September, this Cody problem requires a string for an input. The output will be the same string, but with every fifth letter in the string replaced with 'X'. Numbers, spaces, and punctuation marks are unaffected, which is more than we can say for the government workers.

For example, 'abcde?fgh123ij' would be replaced with 'abcdX?fgh123iX' Good luck!