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
import math
input = sys.stdin.readline

def int_array():
    return list(map(int, input().strip().split()))


def str_array():
    return input().strip().split()

def lower_letters():
    lowercase = []
    for i in range(97, 97+26):
        lowercase.append(chr(i))
    return lowercase
    
def upper_letters():
    uppercase = []
    for i in range(65, 65+26):
        uppercase.append(chr(i))
    return uppercase

######################## TEMPLATE ENDS HERE ########################

n, m = int_array()
min_n = int("1" + "0"*(n-1))
max_n = int("9" + "9"*(n-1))+1

ans = 0
for i in range(min_n, max_n):
    if i % m == 0:
        ans = i
        break
if ans == 0:
    print(-1)
else:
    print(ans)