Kata

You have a string of numbers; starting with the third number each number is the result of an operation performed using the previous two numbers.

Complete the function which returns a string of the operations in order and separated by a comma and a space, e.g. "subtraction, subtraction, addition"

The available operations are (in this order of preference):

1) addition
2) subtraction
3) multiplication
4) division

Notes:

• All input data is valid
• The number of numbers in the input string >= 3
• For a case like "2 2 4" - when multiple variants are possible - choose the first possible operation from the list (in this case "addition")
• Integer division should be used

Example

"9 4 5 20 25"  -->  "subtraction, multiplication, addition"

Because:

9 - 4 = 5   --> subtraction
4 * 5 = 20  --> multiplication
5 + 20 = 25 --> addition