Write a function that takes a string and calculates the number of letters and digits within it. Return the result as an object.
countAll("Hello World") ➞ { "LETTERS": 10, "DIGITS": 0 }
countAll("H3ll0 Wor1d") ➞ { "LETTERS": 7, "DIGITS": 3 }
countAll("149990") ➞ { "LETTERS": 0, "DIGITS": 6 }