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 PYTHON3):

Solution:
import bisect, math

def foo(n, t):
    # if int('9'*n)<t:    return -1
    # if t==2:
    #     return "1"*(n-1) + '2'
    # if t==4:
    #     if n==1:    return 4
    #     else:       return '1'*(n-2)+'20'
    # if t==3:    return '3'+"0"*(n-1)
    # if t==5:    return "1"*(n-1)+'5'
    if t==10 and n==1:
        return -1
    if t!=10:
        return 10**(n-1) * t
    return 10**(n-1)

    

# t = int(input())
for _ in range(1):
    n, m = map(int, input().split())
    print(foo(n, m))
    # print(" ".join(map(str, foo(n, m))))