package yukicoder;

import java.util.Scanner;

public class yukicoder333 {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		long[] a = readLineLongArray(sc);
		
		long count = 0;
		
		if(a[0] < a[1]){
			count = a[0];
		}else{
			count = 2000000000L-a[0];
		}
		
		System.out.println(count);
		
		
		
	}
	protected static long readLineLong(Scanner sc) {
		return Long.parseLong(sc.nextLine());
	}
	
	protected static long[] readLineLongArray(Scanner sc) {
		String split[] = sc.nextLine().split(" ");
		long ret[] = new long[split.length];
		for (int i = 0; i < ret.length; i++) {
			ret[i] = Long.parseLong(split[i]);
		}
		return ret;
	}
	protected static int readLineInt(Scanner sc) {
		return Integer.parseInt(sc.nextLine());
	}
	
	protected static int[] readLineIntArray(Scanner sc) {
		String split[] = sc.nextLine().split(" ");
		int ret[] = new int[split.length];
		for (int i = 0; i < ret.length; i++) {
			ret[i] = Integer.parseInt(split[i]);
		}
		return ret;
	}
	
	protected static double readLineDouble(Scanner sc) {
		return Double.parseDouble(sc.nextLine());
	}
	
	protected static double[] readLineDoubleArray(Scanner sc) {
		String split[] = sc.nextLine().split(" ");
		double ret[] = new double[split.length];
		for (int i = 0; i < ret.length; i++) {
			ret[i] = Double.parseDouble(split[i]);
		}
		return ret;
	}
	
	protected static String readLineString(Scanner sc) {
		return sc.nextLine();
	}
	
	protected static String[] readLineStringArray(Scanner sc) {
		return sc.nextLine().split(" ");
	}

}