IIN

import java.util.Objects;

import java.time.LocalDate;

public class Human {
    String name;
    String surName;
    int age;
    LocalDate dateOfBirth;
    int iin;

    public Human(String name, String surName, int age, LocalDate dateOfBirth, int iin) {
        this.name = name;
        this.surName = surName;
        this.age = age;
        this.dateOfBirth = dateOfBirth;
        this.iin = iin;
    }
    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        Human human = (Human) o;
        return iin == human.iin;
}

    @Override
    public int hashCode() {
        return Objects.hash(iin); // хэш тоже строим по IIN
    }
}

public class Main {
    public static void main(String[] args) {
      Human h1 = new Human("Yerkebulan", "Orda", 30, LocalDate.of(1995, 5, 5), 123456789);
        Human h2 = new Human("Yerkebulan", "Orda", 30, LocalDate.of(1995, 5, 5), 123456789);
        Human h3 = new Human("Almas", "Omarov", 22, LocalDate.of(2003, 3, 3), 987654321);

        System.out.println("h1.equals(h2): " + h1.equals(h2));
        System.out.println("h1.equals(h3): " + h1.equals(h3));

            }
}