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 sys
# sys.stdin = open('input.txt','r')
# sys.stdout = open('output.txt','w')

n,t=map(int,input().split())
if t==10 and n<2:print(-1)
else:
    arr = ['1']*n

    arr = "".join(arr)
    if len(arr)>1:
        arr = int(arr)-1
    else:
        arr = int(arr)
    flag = 0
    while True:
        if arr%t==0:
            flag = 1
            break
        arr += 1

    if flag:
        print(arr)
    else:
        print(-1)