mystrcat(char *s1, const char *s2)
{
    int i = 0;
    int j = 0;

    while (s1[i] != '\0')
    {
        i++;
    }

    while (s2[j] != '\0')
    {
        s1[i] = s2[j];
    
        i++;
        j++;
    }

	s1[i] = '\0';
}

main()
{
	char first[100] = "Mark";

	mystrcat(first, " ");
	mystrcat(first, "Hancock");

	printf("%s\n", first);
}