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:
#                               #
    # author : samars_diary #
    # 14:55:10 | 24-09-2020 #
#                               #

import sys, os.path

if(os.path.exists('input.txt')):
    sys.stdin = open('input.txt',"r")
    sys.stdout = open('output.txt',"w")

sys.setrecursionlimit(10 ** 5)

def i(): return sys.stdin.readline().strip()
def ii(): return int(sys.stdin.readline())
def li(): return list(sys.stdin.readline().strip())
def mii(): return map(int, sys.stdin.readline().split())
def lii(): return list(map(int, sys.stdin.readline().strip().split()))

print=sys.stdout.write

def solve():
    a, b = mii() ; b = str(b)
    if a >= len(b):
        for _ in range(a-len(b)):
            b+='0'
        print(b)
    else:
        print('-1')

for _ in range(1):
    solve()