problem 20

#include <stdio.h>

int main()
{
    int num, fd, ld, sum;

    printf("Enter a number: ");
    scanf("%d", &num);

    ld = num % 10;

    while (num >= 10)
    {
        num /= 10;
    }
    fd = num;

    sum = fd + ld;

    printf("Sum of first and last digit: %d\n", sum);

    return 0;
}

Enter a number: