// ---------- begin input macro ----------
// reference: https://qiita.com/tanakh/items/0ba42c7ca36cd29d0ac8
macro_rules! input {
    (source = $s:expr, $($r:tt)*) => {
        let mut iter = $s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
    ($($r:tt)*) => {
        let s = {
            use std::io::Read;
            let mut s = String::new();
            std::io::stdin().read_to_string(&mut s).unwrap();
            s
        };
        let mut iter = s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
}

macro_rules! input_inner {
    ($iter:expr) => {};
    ($iter:expr, ) => {};
    ($iter:expr, $var:ident : $t:tt $($r:tt)*) => {
        let $var = read_value!($iter, $t);
        input_inner!{$iter $($r)*}
    };
}

macro_rules! read_value {
    ($iter:expr, ( $($t:tt),* )) => {
        ( $(read_value!($iter, $t)),* )
    };
    ($iter:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($iter, $t)).collect::<Vec<_>>()
    };
    ($iter:expr, chars) => {
        read_value!($iter, String).chars().collect::<Vec<char>>()
    };
    ($iter:expr, bytes) => {
        read_value!($iter, String).bytes().collect::<Vec<u8>>()
    };
    ($iter:expr, usize1) => {
        read_value!($iter, usize) - 1
    };
    ($iter:expr, $t:ty) => {
        $iter.next().unwrap().parse::<$t>().expect("Parse error")
    };
}
// ---------- end input macro ----------

fn run() {
    input! {
        n: usize,
        k: usize,
    }
    if k <= 3 {
        if n >= 9 {
            println!("-1");
            return;
        }
        for i in 0..(1 << n) {
            let mut s = vec![];
            for j in 0..n {
                s.push(i >> j & 1);
            }
            let mut v = 1;
            for l in 0..n {
                for r in (l + 2)..=n {
                    let mut b = s[l..r].iter().cloned().collect::<Vec<_>>();
                    b.reverse();
                    if s[l..r] == b[..] {
                        v = v.max(r - l);
                    }
                }
            }
            if v == k {
                let ans = s.into_iter().map(|c| (b'0' + c as u8) as char).collect::<String>();
                println!("{}", ans);
                return;
            }
        }
        println!("-1");
        return;
    }
    let mut ans = String::new();
    while ans.len() < n {
        ans.push('1');
        for _ in 2..k {
            ans.push('0');
        }
        ans.push('1');
        ans.push('1');
        ans.push('0');
    }
    while ans.len() > n {
        ans.pop();
    }
    println!("{}", ans);
}

fn main() {
    run();
}