#include<iostream>
#include<string>
using namespace std;
int main()
{
	string s;
	string ma;
	int pl = 0;
	getline(cin, s);
	for (int i = 0; i < s.size(); i++){
		if (s[i] == '.' || s[i] == ',' || s[i] == ' '){
			ma.clear();
			for (int i2 = pl; i2 < i; i2++){
				ma += s[i2];
			}
			if (s[i] == '.' || s[i] == ','){
				pl = i+2;
			}
			else{
				pl = i+1;
			}
			if (ma.size() >= 3 && ma.size() <= 6 && pl<s.size()){
				cout << ma << " ";
			}
			else if (ma.size() >= 3 && ma.size() <= 6 && pl >= s.size()){
				cout << ma;
			}
		}
	}
	cout << endl;
}