import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;

public class Program3 {

	public static void main(String[] args) {

		HashSet<String> country = new HashSet<String>();
		country.add("India");
		country.add("USA");
		country.add("China");
		country.add("Russia");
		System.out.println(country);

	}
}