Count the digits

Write a function countDigits(n) that returns how many digits the integer n has.

• n is an integer from -999999999999999 to 999999999999999, so it has at most 15 digits. It can be negative or zero.
• The minus sign is not a digit: countDigits(-305) is 3.
• 0 is written with one digit, so countDigits(0) is 1.
• Return a number, for example 5, not the string '5'.