import java.util.*;
import java.lang.*;
import java.io.*;

// The main method must be in a class named "Main".
class Main {
    public static void main(String[] args) {
        Scanner sc=new Scanner(System.in);
        String str1=sc.nextLine();
        int index=0;
        int max_length=0;
        char ch[]=new char[str1.length()];
        Stack<String> st=new Stack<>();
        for(int i=0;i<str1.length();i++){
            if(str1.charAt(i)==',' || str1 .charAt(i)=='.' || str1.charAt(i)=='!' || i==str1.length()-1){
                //System.out.println(max_length+ " "+())
                if(max_length <(i-index)){
                    max_length=i-index;
                    if(!st.isEmpty()){
                        st.pop();
                    }   
                    //System.out.println(str1.substring(index,i));
                    String res=str1.substring(index,i);
                    //System.out.println(res);
                    st.add(res);
                }
              if(i+1<str1.length()-1) index=i+1;
            }
        }
     if(!st.isEmpty()){
         System.out.println(st.peek());
     }
    }
}