Write a program to add two positive integers, each containing up to n digits.
Note that you cannot use int to store these integers, since an int only occupies four bytes and can represent numbers with up to 10 digits.
The program must store the two large integers as strings and perform the addition operation manually.
Due to the digit limitation, the addition can be easily handled using an appropriate data type.
Parameter specification: 0 < n ≤ 18
Two positive integer.
Ex.123456789012345678
987654321098765432
The sum of the integers.
Ex.1111111110111111110