import java.util.*;

public class HashMapTest1 {
    public static void main(String []args) {
        String string1= "ABFED";
        String string2= "AFBHI";

        HashMap<Character,Boolean> hm1 = new HashMap<>();
        
        for (char theChar : string1.toCharArray()){
            hm1.put(theChar ,false);
        }

        for (char theChar : string2.toCharArray()){
            if (hm1.containsKey(theChar)) {
                System.out.print(theChar);
            }
        }
    }
}