After N Months...

Create a function that takes in year and month as input, then return what year it would be after n-months have elapsed.

Examples

after_n_months(2020, 24) ➞ 2022

after_n_months(1832, 2) ➞ 1832

after_n_months(1444, 60) ➞ 1449

Notes

• Assume that adding 12 months will always increment the year by 1.
• If no value is given for year or months, return "year missing" or "month missing".
• At least one value will be present.