#include <cstdio>
#include <vector>
#include <algorithm>
#include <cstring>
#include <string>
#include <cctype>
#include <sstream>
#include <cmath>
#include <climits>
#include <set>
#include <iostream>
#include <map>
#include <functional>
#include <cstdlib>
#include <numeric>
#include <queue>
#include <complex>

using namespace std;

#define reep(i,f,n) for(int i=f; i<int(n); ++i)
#define rep(i,n) reep(i,0,n)

typedef vector<int> vi;
typedef pair<int, int> pii;
typedef complex<double> Point;

int main()
{
	bool first = true;
	char str[2048];
	fgets(str, 2048, stdin);
	rep(i, strlen(str)){
		if(str[i] == '.' || str[i] == ',')
			str[i] = ' ';
	}

	int offset = 0;
	char word[2048];
	while(sscanf(str+offset, "%s", word) != EOF){
		int n = strlen(word);
		if(3<=n && n<=6){
			printf("%s%s", first?"":" ", word);
			first = false;
		}
		offset += n + 1;
	}
	puts("");

	return 0;
}