# A mammoth counting!

**Computer Science**Level 5

Let \(f(n)\) represent the total number of straight line segments in the **UPPER CASE** English representation of the natural number \(n\) without adding **AND** and hyphen (**-**). For example, 12 can be written as **TWELVE** and if you carefully count all the straight-line segments in it, you get \(f(n) = 18\).

Call a number *truthful* if \(f(n) = n\). What is the sum of the all truthful numbers from 1 to 9999?

**Explicit Examples**:

The letters

**G**,**I**,**J**,**Q**,**R**,**U**and**X**contain 1, 1, 0, 1, 2, 0 and 2 straight line segments respectively.Use the word

**ONE**for denoting a single hundred or thousand and don't use the word**AND**anywhere.Some examples of the upper representation are:

73: SEVENTY THREE

105: ONE HUNDRED FIVE

1274: ONE THOUSAND TWO HUNDREDS SEVENTY FOUR

6001: SIX THOUSANDS ONE