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.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.StringTokenizer;

public class CodeForces {
    static reader input = new reader();
    static PrintWriter output = new PrintWriter(System.out);

    public static void main(String[] args) throws IOException {
        /*
        BufferedReader bf = new BufferedReader(new FileReader("input.txt"));
        PrintWriter pw = new PrintWriter(new BufferedWriter(new FileWriter("output.txt")));
        StringTokenizer stk= new StringTokenizer(bf.readLine());;
        int n=Integer.parseInt(stk.nextToken());
        */
        C();
        output.close();
    }

    public static void A(){

    }

    public static void B(){

    }

    public static void C(){
        int n=input.nextInt();
        int m=input.nextInt();
        if(n-m>=2){
            output.println(-1);
        }else{
            if(m>n){
                StringBuilder ans=new StringBuilder("");
                while(m>n&&n>=1){
                    ans.append("110");
                    m-=2;
                    n-=1;
                }
                if(n==0){
                    if(m>=3)
                        output.println(-1);
                    else{
                        for(int i=0;i<m;i++)
                            ans.append("1");
                        output.println(ans);
                    }
                }else{
                    for(int i=0;i<m;i++){
                        ans.append("10");
                    }
                    output.println(ans);
                }
            }else{
                StringBuilder ans=new StringBuilder("");
                for(int i=0;i<m;i++){
                    ans.append("01");
                }
                if(n>m){
                    ans.append("0");
                }
                output.println(ans);
            }
        }
    }

    public static void D(){

    }

    public static void E(){

    }

    public static void F(){

    }

    public static long factorial(int a){
        long ans=1;
        for(int i=1;i<=a;i++){
            ans*=i;
        }
        return ans;
    }
    public static long LCM(long a,long b){
        return (a*b)/GCD(a,b);
    }
    public static long GCD(long a,long b){
        if(a==0)
            return b;
        else if(b==0)
            return a;
        else
            return GCD(b%a,a);
    }

    public static boolean isPrime(long num){
        if(num==1)
            return false;
        else if(num==2||num==3)
            return true;
        else if(num%2==0||num%3==0)
            return false;
        else{
            for(long i=5;i*i<=num;i+=6){
                if(num%i==0||num%(i+2)==0)
                    return false;
            }
        }
        return true;
    }

    public static ArrayList<Integer> SieveofEratothenis(){
        ArrayList<Integer>ans=new ArrayList<>();
        boolean visited[]=new boolean[1000000];
        for(int i=2;i<1000000;i++){
            if(!visited[i]){
                ans.add(i);
                for(long j=(long)i*i;j<1000000;j+=i){
                    visited[(int)j]=true;
                }
            }
        }
        return ans;
    }

    public static void mergesort(long arr[],int start,int end){//start and end must be indexes
        if(start<end) {
            int mid=(start+end)/2;
            mergesort(arr,start,mid);
            mergesort(arr, mid+1, end);
            merge(arr, start,mid,end);
        }
    }
    public static void merge(long arr[],int start,int mid,int end){
        int lsize=mid-start+1,rsize=end-mid;
        long l[]=new long[lsize],r[]=new long[rsize];
        for(int i=start;i<=mid;i++){
            l[i-start]=arr[i];
        }
        for(int i=mid+1;i<=end;i++){
            r[i-mid-1]=arr[i];
        }
        int i=0,j=0,k=start;
        while(i<lsize&&j<rsize){
            if(l[i]<=r[j]){
                arr[k++]=l[i++];
            }else{
                arr[k++]=r[j++];
            }
        }
        while(i<lsize)
            arr[k++]=l[i++];
        while(j<rsize)
            arr[k++]=r[j++];
    }
}

class Value{
    int ans;
}

class Pair{
    int x,y;
    Pair(int x,int y){
        this.x=x;
        this.y=y;
    }
}

class Op{
    int op,count;
    char dir;
    public Op(int op){
        this.op=op;
    }
}

class reader {
    BufferedReader br;
    StringTokenizer st;

    public reader() {
        br = new BufferedReader(new
                InputStreamReader(System.in));
    }

    String next() {
        while (st == null || !st.hasMoreElements()) {
            try {
                st = new StringTokenizer(br.readLine());
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return st.nextToken();
    }

    int nextInt() {
        return Integer.parseInt(next());
    }

    long nextLong() {
        return Long.parseLong(next());
    }

    double nextDouble() {
        return Double.parseDouble(next());
    }

    String nextLine() {
        String str = "";
        try {
            str = br.readLine();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return str;
    }

    public int[] nextIntArray(int arraySize) {
        int array[] = new int[arraySize];
        for (int i = 0; i < arraySize; i++) {
            array[i] = nextInt();
        }
        return array;
    }

    public long[] nextLongArray(int arraySize) {
        long array[] = new long[arraySize];
        for (int i = 0; i < arraySize; i++) {
            array[i] = nextLong();
        }
        return array;
    }
}