int make_friends(const char *name1, const char *name2, User *head) {
    User *curr1 = head;
    User *curr2 = head;
    while (curr1 != NULL && strcmp(curr1->name, name1) != 0) {
        curr1 = curr1->next;
    }
    while (curr2 != NULL && strcmp(curr2->name, name2) != 0) {
        curr2 = curr2->next;
    }
    if (curr1 == NULL || curr2 == NULL) {
        return 4; 
    }
    else if (curr1 == curr2) {
        return 3;
    }
    else if (curr1->friends[MAX_FRIENDS-1] != NULL || curr2->friends[MAX_FRIENDS-1] != NULL) {
        return 2;
    }
    else {
        for (int i = 0; i < MAX_FRIENDS; i++) {
            if (curr1->friends[i] == curr2) {
                return 1;
            }
            else if (curr1->friends[i] == NULL) {
                curr1->friends[i] = curr2;
                for (int j = 0; j < MAX_FRIENDS; j++) {
                    if (curr2->friends[j] == NULL) {
                        curr2->friends[j] = curr1;
                    }
                    else {
                        curr2 = curr2->next;
                    }
                }
            }
            else {
                curr1 = curr1->next;
            }
        }
    }
    return 0;
}
make 2 valid users friends if they are not already friends