#include "bits/stdc++.h"

#define REP(i,num) for(int i=0;i<(num);++i)
#define ALL(c) c.begin(),c.end()
#define LOOP(i) while(i--)
#define PRINTALL(c) for(auto& x:c){cout<<x<<' ';}cout<<endl;
#define PAIRCOMP(c,comp) [](const pair<ll,ll>& lhs,const pair<ll,ll>& rhs){return lhs.c comp rhs.c;}

using namespace std;
using ll = long long;

constexpr ll atcoder_mod = 1e9+7;

template<typename T=int>
T in(){T x; cin >> x; return (x);}
template<typename T=int,typename C=vector<T>>
C vecin(int N){C x(N);REP(i,N){x[i]=in<T>();}return move(x);}

void vout(){cout << endl;}
template<typename Head,typename... Tail>
void vout(Head&& h,Tail&&... t){cout << ' ' << h;vout(forward<Tail>(t)...);}
void out(){cout << endl;}
template<typename Head,typename... Tail>
void out(Head&& h,Tail&&... t){cout << h;vout(forward<Tail>(t)...);}

vector<string> split_naive(const string &s,vector<char>& delim) {
	vector<string> elems;
	string item;
	for(char ch:s){
		bool exist = false;
		for(auto del:delim){
			if(ch==del){
				if(!item.empty()) elems.push_back(item);
				item.clear();
				exist = true;
				break;
			}
		}
		if(!exist){
			item += ch;
		}
	}
	if(!item.empty()) elems.push_back(item);
	return elems;
}

int main(){
	cin.tie(0);
	ios::sync_with_stdio(false);

	char str[1030];
	vector<char> delim={' ',',','.'};
	vector<string> S;
	while(cin.getline(str,sizeof(str))){
		auto T = split_naive(str,delim);
		for(auto u:T){
			if(u.size()>=3 && u.size()<=6) S.push_back(u);
		}
	}
	int N=S.size();
	REP(i,N-1){
		cout << S[i] << ' ';
	}
	if(!S.empty()) out(S.back());
	return 0;
}
