import java.time.Instant;
import java.time.temporal.ChronoUnit;

public class Main {
	public static void main(String[] args) {
		Instant instant1 = Instant.parse("2021-03-23T04:17:35Z");
		Instant instant2 = Instant.parse("2021-07-15T05:27:00Z");

		System.out.println(instant1);
		System.out.println(instant2);

		System.out.println(ChronoUnit.HOURS.between(instant1, instant2));
	}
}