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) {
        System.out.println("Hello world!");
    }
}

abstract class TypeReference<T> {
    private final Type type;

    protected TypeReference() {
        Type superClass = getClass().getGenericSuperclass();
        if (superClass instanceof Class) {
            throw new IllegalArgumentException("Type parameter missing");
        }
        this.type = ((ParameterizedType) superClass).getActualTypeArguments()[0];
    }

    public Type getType() {
        return this.type;
    }
}