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:
// var _i = 0;
//
// function readline() {
//     _i ++;
//
//     switch (_i) {
//         case 1: return '1 10';
//     }
// }
//
// function write(value) {
//     console.log(value);
// }

function getDigitsCount(n) {
    var res = 0;

    while (n > 0) {
        n = Math.floor(n / 10);
        res ++;
    }

    return res;
}

var a = readline().split(' ');

var n = parseInt(a[0]);
var t = parseInt(a[1]);

var m = getDigitsCount(t);
var ans;

if (n < m) {
    ans = -1;
} else {
    ans = t;

    for (var i = 0; i < n-m; i ++) {
        ans = ans + '0';
    }
}

write(ans);