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:
/*input
1 5



*/
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.*;
public class Main {
   InputStream is;
	PrintWriter out;
	String INPUT = ""; 
//class Declaration
static class pair implements Comparable<pair>{
    int x,y;
    pair (int i,int j)
    { x=i; y=j;}
    public int compareTo(pair p){
        if(this.x!=p.x) { return this.x-p.x;}
        else { return this.y-p.y;}
    }
    public int hashCode() { return (x+" "+y).hashCode();}
    public String toString(){ return x+" "+y;} 
    public boolean equals(pair x){ return (x.x==this.x&&x.y==this.y);}
}



void solve(){ 
int n=ni(),m=ni();
StringBuilder ans=new StringBuilder();
if(2*(n+1)<m) pn(-1);
else if(m<n-1) pn(-1);
else{
	if(m==n-1){
		n--;
		ans.append(0);
		for(int i=0;i<n;++i){
			ans.append("10");
		}
		//pn(ans);

	}
	else{
	while(n>0){
		if(m==n){
			for(int i=0;n-->0;++i){
				ans.append("10");
				m--;
			}

		}
		else{
			ans.append("11");
			ans.append("0");
			m-=2;n--;

		}
	}
	while(m-->0) ans.append(1);
}
}
pn(ans);






}



int min(int[] arr)
{
    int min=Integer.MAX_VALUE;
    for(int i=0;i<arr.length;++i)
    {
        if(min>arr[i]) min=arr[i];
    }
    return min;
}
int max(int[] arr)
{
    int max=Integer.MIN_VALUE;
    for(int i=0;i<arr.length;++i)
    {
        if(max<arr[i]) max=arr[i];
    }
    return max;
}
static int gcd(int x,int y)
{
  if(y==0) return x;
  return gcd(y,x%y);
}
static long nCr(long n,long rc)
{
 long r=Math.min(rc,n-rc);
 long ans=1;
 for(int i=1,j=(int)n;i<=r;++i,--j)
 {
   ans=(ans*(long)j)/((long)i);
 }
  return ans;
  
}

void run() throws Exception
{
		is = INPUT.isEmpty() ? System.in : new ByteArrayInputStream(INPUT.getBytes());
		out = new PrintWriter(System.out);
		
		long s = System.currentTimeMillis();
		solve();
		out.flush();
		if(!INPUT.isEmpty())tr(System.currentTimeMillis()-s+"ms");
}
	
	
	public static void main(String[] args) throws Exception { new Main().run(); }
	
//output methods
private void pn(Object o)
{
	out.println(o);
}
private void p(Object o)
{
	out.print(o);
}



//input methods
		private byte[] inbuf = new byte[1024];
	public int lenbuf = 0, ptrbuf = 0;
	

	private int readByte()
	{
		if(lenbuf == -1)throw new InputMismatchException();
		if(ptrbuf >= lenbuf){
			ptrbuf = 0;
			try { lenbuf = is.read(inbuf); } catch (IOException e) { throw new InputMismatchException(); }
			if(lenbuf <= 0)return -1;
		}
		return inbuf[ptrbuf++];
	}
	
	private boolean isSpaceChar(int c) { return !(c >= 33 && c <= 126); }
	private int skip() { int b; while((b = readByte()) != -1 && isSpaceChar(b)); return b; }
	
	private double nd() { return Double.parseDouble(ns()); }
	private char nc() { return (char)skip(); }
	
	private String ns()
	{
		int b = skip();
		StringBuilder sb = new StringBuilder();
		while(!(isSpaceChar(b))){ // when nextLine, (isSpaceChar(b) && b != ' ')
			sb.appendCodePoint(b);
			b = readByte();
		}
		return sb.toString();
	}
	
	private char[] ns(int n)
	{
		char[] buf = new char[n];
		int b = skip(), p = 0;
		while(p < n && !(isSpaceChar(b))){
			buf[p++] = (char)b;
			b = readByte();
		}
		return n == p ? buf : Arrays.copyOf(buf, p);
	}
		
	private char[][] nm(int n, int m)
	{
		char[][] map = new char[n][];
		for(int i = 0;i < n;i++)map[i] = ns(m);
		return map;
	}
	
	private int[] na(int n)
	{
		int[] a = new int[n];
		for(int i = 0;i < n;i++)a[i] = ni();
		return a;
	}
	
	private int ni()
	{
		int num = 0, b;
		boolean minus = false;
		while((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'));
		if(b == '-'){
			minus = true;
			b = readByte();
		}
		
		while(true){
			if(b >= '0' && b <= '9'){
				num = num * 10 + (b - '0');
			}else{
				return minus ? -num : num;
			}
			b = readByte();
		}
	}
	
	private long nl()
	{
		long num = 0;
		int b;
		boolean minus = false;
		while((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'));
		if(b == '-'){
			minus = true;
			b = readByte();
		}
		
		while(true){
			if(b >= '0' && b <= '9'){
				num = num * 10 + (b - '0');
			}else{
				return minus ? -num : num;
			}
			b = readByte();
		}
	}
	
	private void tr(Object... o) { if(INPUT.length() > 0)System.out.println(Arrays.deepToString(o)); }
}