#include <bits/stdc++.h>
using namespace std;

int main() {
	ios::sync_with_stdio(false); cin.tie(nullptr);
	int n; cin >> n;
	unordered_set<string> vis;
	vector<string> ans;
	for (int i = 0; i < n; i++) {
		string name; cin >> name;
		if (!vis.count(name)) {
			vis.insert(name); ans.push_back(name);
		}
	}
	cout << ans.size() << '\n';
	for (auto &name : ans) cout << name << '\n'; 
	return 0;
}

#include <bits/stdc++.h>
using namespace std;

int main() {
	ios::sync_with_stdio(false); cin.tie(nullptr);
	int n; cin >> n;
	set<string> vis;
	vector<string> ans;
	for (int i = 0; i < n;i ++) {
		string name; cin >> name;
		if (!vis.count(name)) {
			vis.insert(name);ans.push_back(name);
		}
	}
	cout << ans.size() << '\n';
	for (auto name : ans) cout << name << '\n';
	return 0;
}