import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {

	public static void main(String[] args) throws NumberFormatException,
			IOException {
		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
		String line;
		StringBuilder ans = new StringBuilder();
		while ((line = in.readLine()) != null) {
			String[] t = line.split(" ");
			int H1 = Integer.parseInt(t[0]);
			int M1 = Integer.parseInt(t[1]);
			int H2 = Integer.parseInt(t[2]);
			int M2 = Integer.parseInt(t[3]);

			if (H1 == 0 && H2 == 0 && M1 == 0 && M2 == 0)
				break;
			int start = H1 * 60 + M1;
			int end = H2 * 60 + M2;
			int mins = end - start;
			if (mins < 0)
				mins = mins + 1440;
			ans.append(mins).append("\n");
		}
		System.out.print(ans.toString());
	}
}