public class Main{
public static void main(String[] args){
Scanner scan = new Scanner(System.in);
int[] arr = new int[4];
for(int i = 0; i < arr.length; i++){
arr[i] = scan.nextInt();
}
int res = (arr[3] - arr[1]) > 0 ? (arr[3] - arr[1] + 60 * (arr[2] - arr[0])) :
(arr[3] + 60 - arr[1] + 60 * (arr[2] - arr[0] - 1));
System.out.println(res);
}
}