#include<bits/stdc++.h>
    using namespace std;
    int main()
    {
        int a,b,c=1;
        cin>>a>>b;

        if(a == 1 && b == 10)
        {
            cout<< -1 <<endl;
        }
        else
        {
            cout<<b;
            if(b==10) c++;
            for(c;c<a;c++) cout<< 0;
        }
    }