584A. Olesya and Rodion

constructive algorithm, math, 1000, https://codeforces.com/problemset/problem/584/A

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

n,t = [int(i) for i in input().split()]

if t==10 and n==1:
        print(-1)
elif t==10 and n>1:
        for i in range(n-1):
                print(1, end='')

        print(0)

else:
        for i in range(n):
                print(t, end='')

        print()