missing default ctor

person.java

package com.alex.constructors;

class Person {

    String name;
    String surname;
    int age;

    Person(String n, String s, int a) {
        name = n;
        surname = s;
        age = a;
    }

    void print() {
        System.out.println(name + " " + surname + ", " + age + " лет.");
    }
}

class Program {

    public static void main(String[] args) {
        Person a = new Person("Petr", "Petrov", 47);
        Person b = new Person();
        // constructor Person in class Person cannot be applied to given types;
        // required: String,String,int
        // found: no arguments
        // reason: actual and formal argument lists differ in length
        a.print();
        b.print();
    }
}