content: package v116;
  import java.io.BufferedReader;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.InputStreamReader;
  import java.io.PrintWriter;
  import java.util.StringTokenizer;
  
  public class AlarmClock_UVa11677 {
  	
  	public static void main(String[] args) throws IOException {
  		Scanner sc = new Scanner(System.in);
  		PrintWriter out = new PrintWriter(System.out);
  	
  		while(true)
  		{
  			int h1 = sc.nextInt(), m1 = sc.nextInt(), h2 = sc.nextInt(), m2 = sc.nextInt();
  			if(h1 + h2 + m1 + m2 == 0)
  				break;
  			int t1 = h1 * 60 + m1, t2 = h2 * 60 + m2;
  			out.println((t2 - t1 + 60 * 24) % (60 * 24));
  		}
  		out.flush();
  		out.close();
  	}
  
  	static class Scanner 
  	{
  		StringTokenizer st;
  		BufferedReader br;
  
  		public Scanner(InputStream s){	br = new BufferedReader(new InputStreamReader(s));}
  
  		public String next() throws IOException 
  		{
  			while (st == null || !st.hasMoreTokens()) 
  				st = new StringTokenizer(br.readLine());
  			return st.nextToken();
  		}
  
  		public int nextInt() throws IOException {return Integer.parseInt(next());}
  
  		public long nextLong() throws IOException {return Long.parseLong(next());}
  
  		public String nextLine() throws IOException {return br.readLine();}
  
  		public double nextDouble() throws IOException { return Double.parseDouble(next()); }
  
  		public boolean ready() throws IOException {return br.ready();} 
  	}
  } 