#include<bits/stdc++.h>
#define REP(i,n) for(int i=0;i<n;i++)
#define LOOP(i,x,n) for(int i=x;i<n;i++)
#define ALL(v) (v).begin(),(v).end()
#define PB push_back
#define MP make_pair
#define FR first
#define SC second
#define int long long
using namespace std;
const int MOD=1000000007;
const int INF=9000000009;

signed main(){
  string s;
  while(getline(cin,s)){
    string t;
    REP(i,s.size()){
      if(s[i]==','||s[i]==' '||s[i]=='.'){
        if(2<t.size()&&t.size()<7){
          cout<<t<<' ';
        }
        t="";
      }else{
        t+=s[i];
      }
    }
    cout<<endl;
  }
  return 0;
}

