#include <iostream>
#include <queue>
#include <stack>
#include <vector>
#include <stdio.h>
#include <algorithm>
#include <string.h>
#include <string>
#include <cmath>
#include <complex>
#include <map>
using namespace std;

#define rep(i,n) for(int i=0;i<int(n);++i)
#define ALL(v) (v).begin(),(v).end()
#define PB push_back
#define EPS 1e-8
#define F first
#define S second

static const double PI=6*asin(0.5);
typedef pair<double,double> P;
typedef complex<double> CP;
typedef long long ll;

string s;
string tmp;

int main(){
	getline(cin,s);
	bool f=false;
	rep(i,s.size()){
		if(s[i]==32||s[i]==','||s[i]=='.'){
			if(tmp.size()>=3&&tmp.size()<7){
				if(f) cout<<" ";
				cout<<tmp;
				f=true;
			}
			tmp.clear();
		}
		else{
			tmp+=s[i];
		}
	}
	cout<<endl;
	return 0;
}