DIY: Multiply Strings

Problem statement

You are given two non-negative integers represented as strings. Your task is to find the product of the given two integer numbers in the form of a string. For this, you will first convert the given strings to an integer without using the built-in library and then use the multiplication operator.

Constraints

• 1 <= first_number.length, second_number.length <= 200
• first_number and second_number consist of digits only.
• The first_number and the second_number do not contain any leading zero, except the number 0 itself.

Input

The inputs to the function are strings with integer values. The following is an example input:

first_number = 5
second_number = 6

Output

The following is the output of the above input:

30

Coding exercise

Implement the function multiply(first_number, second_number), which accepts two string arguments first_number and second_number storing non-negative integer numbers and returns the product of the two integers as a string.