#include <stdio.h>

#define SIZE 5
 
main() 
{
	char number1[SIZE]; /* stores the first number */
	char number2[SIZE]; /* stores the second number */
	char number3[SIZE]; /* stores the addition */
	char symbol; /* stores the current symbol read */
	int i;
	int carry; /* records the carry value during addition */

	/* read the first number */
	printf("Enter a %d digit number: ", SIZE);

	for (i = 0; i < SIZE; i++) {
		number1[i] = getchar() - 48;
	}

	/* read the second number */
	printf("Enter another %d digit number: ", SIZE);

	for (i = 0; i < SIZE; ) {
		symbol = getchar();
		if ((symbol >= '0') && (symbol <= '9')) { /* ignore non-digits */
			number2[i] = symbol - 48;
			i++;
		}
	}


	/* add two numbers */
	carry = 0; /* initial carry is 0 */
	for (i = SIZE-1; i >= 0; i--) {
		number3[i] = number1[i] + number2[i] + carry;	
		if (number3[i] >= 10) { /* carry is 1 */
			number3[i] = number3[i] - 10;
			carry = 1;
		}
		else /* carry is 0 */
			carry = 0;
	}

	if (carry == 1) { /* shift digits of number3 */
		for (i = SIZE; i > 0; i--)
			number3[i] = number3[i-1];

		number3[0] = 1;
	}	

	/* output the result */
	printf("The sum is: ");
	
	if (carry == 1) { /* number3 has SIZE+1 digits */
		for (i = 0; i <= SIZE; i++)
			printf("%c", number3[i]+48);
	}
	else { /* number3 has SIZE digits */
		for (i = 0; i < SIZE; i++)
			printf("%c", number3[i]+48);
	}

	printf("\n");
}