import java.time.Instant;
import java.time.LocalDateTime;
import java.time.ZoneId;

public class Main {
	public static void main(String[] args) {
		String strDate = "2021-11-25";
		String strTime = "15:20";
		String strDateTime = strDate + "T" + strTime;
		LocalDateTime ldt = LocalDateTime.parse(strDateTime);
		Instant instant = ldt.atZone(ZoneId.systemDefault()).toInstant();
		System.out.println(instant);
	}
}