백준 1181 c++

#include <iostream>
#include <algorithm>
#include <cstring>

using namespace std;

int input(int lower, int upper);
void input_word(string* word, int size);
void sort_word(string* word, int size);
void print_word(string* word, int size);
bool compare(string front, string back);

int main(void)
{
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	cout.tie(NULL);

	int N;
	int i;
	string* word;

	N = input(1, 20000);
	word = new string[N];

	input_word(word, N);
	sort_word(word, N);
	print_word(word, N);
	
	delete[] word;

	return 0;
}

int input(int lower, int upper)
{
	int A;

	while (1)
	{
		cin >> A;
		if (A >= lower && A <= upper)
		{
			break;
		}
		else
		{
			;
		}
	}

	return A;
}

void input_word(string *word, int size)
{
	int i;

	for (i = 0; i < size; i++)
	{
		cin >> word[i];
	}

	return;
}

void sort_word(string *word, int size)
{
	sort(word, word + size, compare);

	return;
}

void print_word(string* word, int size)
{
	int i;
	for (i = 0; i < size; i++)
	{
		if (word[i] == word[i + 1])
		{
			;
		}
		else
		{
			cout << word[i] << '\n';
		}
	}

	return;
}

bool compare(string front, string back)
{
	if (front.length() == back.length())
	{
		return front < back;
	}
	else
	{
		return front.length() < back.length();
	}
}