Problem: Now it's time of Olympiads. Vanya and Egor decided to make his own team to take part in a programming Olympiad. They've been best friends ever since primary school and hopefully, that can somehow help them in teamwork.

For each team Olympiad, Vanya takes his play cards with numbers. He takes only the cards containing numbers 1 and 0. The boys are very superstitious. They think that they can do well at the Olympiad if they begin with laying all the cards in a row so that:

  * there wouldn't be a pair of any side-adjacent cards with zeroes in a row; 
  * there wouldn't be a group of three consecutive cards containing numbers one. 



Today Vanya brought n cards with zeroes and m cards with numbers one. The number of cards was so much that the friends do not know how to put all those cards in the described way. Help them find the required arrangement of the cards or else tell the guys that it is impossible to arrange cards in such a way.

Input

The first line contains two integers: n (1 ≤ n ≤ 106) — the number of cards containing number 0; m (1 ≤ m ≤ 106) — the number of cards containing number 1.

Output

In a single line print the required sequence of zeroes and ones without any spaces. If such sequence is impossible to obtain, print -1.

Examples

Input

1 2


Output

101


Input

4 8


Output

110110110101


Input

4 10


Output

11011011011011


Input

1 5


Output

-1

Solution (in JAVA):

Solution:
import java.io.*;
import java.math.*;
import java.util.*;
import java.util.concurrent.ArrayBlockingQueue;


public class Main {

	InputReader in;
	PrintWriter out;

	void run(){
		/*try {
			out = new PrintWriter(new FileOutputStream("output.txt"));
			in = new InputReader(new FileInputStream("input.txt"));
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		}*/
		out = new PrintWriter(new OutputStreamWriter(System.out));
		in = new InputReader(System.in);
		solve();
		out.flush();
	}

	public static void main(String[] args){
		new Main().run();
	}
	
	
	void solve() {
		int nz = in.ni();
		int n1 = in.ni();
		if(n1 != nz)
			if((nz > n1 + 1) || n1 > 2*(nz + 1)) {
				out.println("-1");
				return;
			}
		StringBuilder sb = new StringBuilder();
		if(nz == n1) {
			while(nz > 0) {
				sb.append("0");
				sb.append("1");
				nz--;
			}
		}
		else if(nz == n1 + 1) {
			while(nz > 1) {
				sb.append("0");
				sb.append("1");
				nz--;
			}
			sb.append("0");
		}
		else {
			int[] place = new int[nz+1];
			for(int i = 0; i < nz + 1; i++) {
				place[i]++;
				n1--;
			}
			for(int i = 0; i < nz + 1; i++) {
				if(n1 == 0)
					break;
				place[i]++;
				n1--;
			}
			for(int i = 0; i < nz; i++) {
				for(int j = 0; j < place[i]; j++)
					sb.append("1");
				sb.append("0");
			}
			for(int j = 0; j < place[nz]; j++)
				sb.append("1");
		}
		out.println(sb.toString());
	}
	
	class InputReader {
		private boolean finished = false;
		private InputStream stream;
		private byte[] buf = new byte[1024];
		private int curChar;
		private int numChars;
		private SpaceCharFilter filter;

		public InputReader(InputStream stream) {
			this.stream = stream;
		}

		public int read() {
			if (numChars == -1)
				throw new InputMismatchException();
			if (curChar >= numChars) {
				curChar = 0;
				try {
					numChars = stream.read(buf);
				} catch (IOException e) {
					throw new InputMismatchException();
				}
				if (numChars <= 0)
					return -1;
			}
			return buf[curChar++];
		}

		public int peek() {
			if (numChars == -1)
				return -1;
			if (curChar >= numChars) {
				curChar = 0;
				try {
					numChars = stream.read(buf);
				} catch (IOException e) {
					return -1;
				}
				if (numChars <= 0)
					return -1;
			}
			return buf[curChar];
		}

		public int ni() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			int sgn = 1;
			if (c == '-') {
				sgn = -1;
				c = read();
			}
			int res = 0;
			do {
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = read();
			} while (!isSpaceChar(c));
			return res * sgn;
		}

		public long nl() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			int sgn = 1;
			if (c == '-') {
				sgn = -1;
				c = read();
			}
			long res = 0;
			do {
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = read();
			} while (!isSpaceChar(c));
			return res * sgn;
		}

		public String ns() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			StringBuilder res = new StringBuilder();
			do {
				res.appendCodePoint(c);
				c = read();
			} while (!isSpaceChar(c));
			return res.toString();
		}

		public boolean isSpaceChar(int c) {
			if (filter != null)
				return filter.isSpaceChar(c);
			return isWhitespace(c);
		}

		public boolean isWhitespace(int c) {
			return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
		}

		private String readLine0() {
			StringBuilder buf = new StringBuilder();
			int c = read();
			while (c != '\n' && c != -1) {
				if (c != '\r')
					buf.appendCodePoint(c);
				c = read();
			}
			return buf.toString();
		}

		public String readLine() {
			String s = readLine0();
			while (s.trim().length() == 0)
				s = readLine0();
			return s;
		}

		public String readLine(boolean ignoreEmptyLines) {
			if (ignoreEmptyLines)
				return readLine();
			else
				return readLine0();
		}

		public BigInteger readBigInteger() {
			try {
				return new BigInteger(ns());
			} catch (NumberFormatException e) {
				throw new InputMismatchException();
			}
		}

		public char readCharacter() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			return (char) c;
		}

		public double readDouble() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			int sgn = 1;
			if (c == '-') {
				sgn = -1;
				c = read();
			}
			double res = 0;
			while (!isSpaceChar(c) && c != '.') {
				if (c == 'e' || c == 'E')
					return res * Math.pow(10, ni());
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = read();
			}
			if (c == '.') {
				c = read();
				double m = 1;
				while (!isSpaceChar(c)) {
					if (c == 'e' || c == 'E')
						return res * Math.pow(10, ni());
					if (c < '0' || c > '9')
						throw new InputMismatchException();
					m /= 10;
					res += (c - '0') * m;
					c = read();
				}
			}
			return res * sgn;
		}

		public boolean eof() {
			int value;
			while (isSpaceChar(value = peek()) && value != -1)
				read();
			return value == -1;
		}

		public String next() {
			return ns();
		}

		public SpaceCharFilter getFilter() {
			return filter;
		}

		public void setFilter(SpaceCharFilter filter) {
			this.filter = filter;
		}
	}
	public interface SpaceCharFilter {
		public boolean isSpaceChar(int ch);
	}

}