automaton: design a DFA to generate a decimal number

An input alphabet consists of the following symbols ONE, TWO, THREE … HUNDREDS. Design a DFA that accepts entries such as the English representation (for example, ONE HUNDRED AND THIRTY FIVE) of any number from 1 to 999 and generates the equivalent decimal number (135 in this case).

From the "Suggested Exercises" section (at the end of the book) of "Compiler Design Principles" by Aho and Ullman.