import java.util.Scanner; public class Main{ public static void main(String []args){ Scanner sc = new Scanner(System.in); int num1 = sc.nextInt(); int num2 = sc.nextInt(); int num3 = sc.nextInt(); int num4 = sc.nextInt(); //统一将小时化为分钟 int result=(num1*60+num2)-(num3*60+num4); System.out.println(Math.abs(result)); } }