Write a syntax grammar for the language consisting of strings that have n copies the letter a followed by 2n copies of the letter b, and ends with n copies of letter c. i.e.

L = {aⁿb^n+mc^m | n, m > 0}

For example, abc, abbc, aabbcc, aabbbc, abbbcc, , are in the language; however, a, b, c, bc, ac, ab, bac, cab, abbcc, , are not in the language.