int find_substr(char *str, char *substr, int number_pos)
{
    for (number_pos, j = 0; str[number_pos] != '\0'; number_pos++, j = 0) {
        for (; substr[j] != '\0'; j++) {
            if (str[number_pos + j] != substr[j])
            {
                j = -1;
                break;
            }
            if (j != -1) return number_pos;
        }
    }
    return -1;
}