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.util.*;
        import java.math.*;
        import java.lang.*;

        public class Main implements Runnable 
        {
            static class InputReader 
            {
                private InputStream stream;
                private byte[] buf = new byte[1024];
                private int curChar;
                private int numChars;
                private SpaceCharFilter filter;
                private BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

                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 String nextLine()
                {
                    String str = "";
                    try
                    {
                        str = br.readLine();
                    }
                    catch (IOException e)
                    {
                        e.printStackTrace();
                    }    
                    return str;
                }
                public int nextInt() 
                {
                    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 nextLong() 
                {
                    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 double nextDouble() 
                {
                    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, nextInt());
                        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, nextInt());
                            if (c < '0' || c > '9')
                                throw new InputMismatchException();
                            m /= 10;
                            res += (c - '0') * m;
                            c = read();
                        }
                    }
                    return res * sgn;
                }
            
                public String readString() 
                {
                    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 c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
                }
            
                public String next()
                {
                    return readString();
                }
                
                public interface SpaceCharFilter
                {
                    public boolean isSpaceChar(int ch);
                }
            }
            public static void main(String args[]) throws Exception 
            {
                new Thread(null, new Main(),"Main",1<<27).start();
            }
            
            static class Pair{
                int f;
                int s;
                PrintWriter w;

                //int t;
                
                
                // Pair(int f,int s,int t){
                Pair(int f,int s, PrintWriter w){
                    this.f = f;
                    this.s = s;
                    this.w = w;
                    //this.t = t;
                    
                }
                
                public static Comparator<Pair> wc = new Comparator<Pair>(){
                    public int compare(Pair e1,Pair e2){
                    
                        //1 for swap 
                        if(Math.abs(e1.f)-Math.abs(e2.f)!=0){
                            //e1.w.println("**"+e1.f+" "+e2.f);
                            return (Math.abs(e1.f)-Math.abs(e2.f));
                        }
                        else{
                            //e1.w.println("##"+e1.f+" "+e2.f);
                            return (Math.abs(e1.s)-Math.abs(e2.s));
                        }

                        
                    }
                };	
            }

            public static long gcd(long a,long b){
                if(b==0)return a;
                else return gcd(b,a%b);
            }


            ////recursive BFS
            public static int bfsr(int s,ArrayList<Integer>[] a,boolean[] b,int[] pre){
                b[s]=true;
                int p = 1;
                int n = pre.length -1;
                int t = a[s].size();
                int max = 1;
                for(int i=0;i<t;i++){
                    int x = a[s].get(i);
                    if(!b[x]){
                        //dist[x] = dist[s] + 1;
                        int xz =  (bfsr(x,a,b,pre));
                        p+=xz;
                        max = Math.max(xz,max);
                    }
                }
                //max = Math.max(max,(n-p));
                pre[s] = max;
                return p;
            }   

        //// iterative BFS
            public static int bfs(int s,ArrayList<Integer>[] a,int dist,boolean[] b,PrintWriter w){
                b[s]=true;
                int siz = 0;
                dist--;
                Queue<Integer> q = new LinkedList<>();
                q.add(s);
                while(q.size()!=0 && dist>0 ){
                    int i=q.poll();
                    Iterator<Integer> it = a[i].listIterator();
                    int z=0;
                    while(it.hasNext() && dist>0){
                        z=it.next();
                        if(!b[z]){
                            b[z]=true;
                            dist--;
                            //dist[z] = dist[i] + 1;
                            siz++;
                            q.add(z);
                        }
                    }   
                
                }
                return siz;
            }

            public static int lower(int key, Integer[] a){
                int l = 0;
                int r = a.length-1;
                int res = 0;

                while(l<=r){
                    int mid = (l+r)/2;

                    if(a[mid]<=key){
                        l = mid+1;
                        res = mid+1;
                    }
                    else{
                        r = mid -1;
                    }
                }

                return res;
            }

            

            

        //////////////////////////////////////////////////////////////////////////////////////////////////////
        //////////////////////////////////////////////////////////////////////////////////////////////////////


            public void run()
            {
                InputReader sc = new InputReader(System.in);
                PrintWriter w = new PrintWriter(System.out);
                long defaultValue = 0;
                

                
                // int tc = sc.nextInt();
                // while(tc-->0){
                    int n = sc.nextInt();
                    int m = sc.nextInt();
                    
                    if(n>=m){
                        if((n-m)>1){
                            w.println(-1);
                        }
                        else{
                            for(int i=0;i<(n+m);i++){
                                w.print((i%2));
                            }
                        }
                    }
                    else{
                        if(m>((n+1)*2)){
                            w.println(-1);
                        }
                        else if(m>=(n)*2){
                            for(int i=0;i<n;i++){
                                w.print("110");
                                m-=2;
                            }
                            for(int i=0;i<m;i++){
                                w.print(1);
                            }
                        }
                        else{
                            int z = (m-n);
                            for(int i=0;i<z;i++){
                                w.print("110");
                                m-=2;
                                n--;
                            }
                            for(int i=m;i>0;i--){
                                w.print(1);
                                if(n>0){
                                    w.print(0);
                                    n--;
                                }
                                m--;
                            }

                        }
                    }
                
                    
                    
                        





                    


                    
                    

                    
                //}
                w.flush();
                w.close();
            }
            
        
            

            
        }