#include <iostream>
#include <queue>
#include <string>
using namespace std;

int main() {
	freopen("input.txt", "r", stdin);
	freopen("output.txt", "w", stdout);
	char a;
	string answer = "";
	int word_length = 0;
	while (cin.get(a)) {
		if ((a >= 'a' && a <= 'z') || (a == ' ') || (a >= 'A' && a <= 'Z') || (a >= '0' && a <= '9')) {
			if (a != ' ')
				word_length++;
			if (a >= 'A' && a <= 'Z') {
				char ch((int)a + 32);
				answer += ch;
			}
			else
				answer += a;
		}
		if (a == ' ') {
			// cout << answer << " " << word_length << endl;
			if (word_length <= 3) {
				for (int j = 0; j <= word_length; j++)
					answer.pop_back();
			}
			word_length = 0;
		}
	}
	if (word_length <= 3 && word_length > 0)
		for (int i = 0; i < word_length; i++)
			answer.pop_back();
	cout << answer;


	return 0;
}