#include <stdio.h>

int SumOfDigits(int num)
{
    int sum = 0;
    if (num < 0)
        return -1;
    while (num > 0)
    {
        sum += (num % 10);
        num /= 10;
    }
    return sum;
}

void main()
{
    printf( "\nPart E - SumOfDigits\n" );
    if( SumOfDigits( -5 ) != -1 )
        printf( "your SumOfDigits(-5) function is wrong (-2)\n" );

    if( SumOfDigits( 19 ) != 1 )
        printf( "your SumOfDigits(19) function is wrong (-2)\n" );

    if( SumOfDigits( 654987 ) != 3 )
        printf( "your SumOfDigits(654987) function is wrong (-2)\n" );

    if( SumOfDigits( 1009 ) != 1 )
        printf( "your SumOfDigits(1009) function is wrong (-2)\n" );
}