Problem: Olesya loves numbers consisting of n digits, and Rodion only likes numbers that are divisible by t. Find some number that satisfies both of them.

Your task is: given the n and t print an integer strictly larger than zero consisting of n digits that is divisible by t. If such number doesn't exist, print  - 1.

Input

The single line contains two numbers, n and t (1 ≤ n ≤ 100, 2 ≤ t ≤ 10) — the length of the number and the number it should be divisible by.

Output

Print one such positive number without leading zeroes, — the answer to the problem, or  - 1, if such number doesn't exist. If there are multiple possible answers, you are allowed to print any of them.

Examples

Input

3 2


Output

712

Solution (in JAVA):

Solution:
try {require('codef');} catch (e){global = this};
function readLineAsArray(separator){return readline().split(typeof separator == "undefined" ? ' ' : separator)}
function readLineAsIntegerArray(separator){return readLineAsArray(separator).map(function(v){return +v})}
Array.prototype.list = function() {var length = arguments.length; for(var i=0; i < length; i++){global[arguments[i]] = this[i]}};
String.prototype.repeat = function(n){return new Array(n + 1).join(this);}

readLineAsIntegerArray().list('n', 't');

write(n == 1 && t == 10 ? -1 : (n == 1 ? t : t * 2 + (t * 2 < 10 ? '0' : '') + ('0').repeat(n - 2)))