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:
from collections import deque
from collections import OrderedDict
import math
 
import sys
import os
import threading
import bisect

import operator
 
import heapq


from atexit import register
from io import BytesIO

#sys.stdin = BytesIO(os.read(0, os.fstat(0).st_size))
#sys.stdout = BytesIO()
#register(lambda: os.write(1, sys.stdout.getvalue()))


import io
#input = io.BytesIO(os.read(0, os.fstat(0).st_size)).readline
#sys.stdin = open("F:\PY\\test.txt", "r")
input = lambda: sys.stdin.readline().rstrip("\r\n")
#input = sys.stdin.readline

 
 
n, m = map(int, input().split())
if m!=10:
    for i in range(n):
        print(m, end="")
else:
    if n==1:
        print(-1)
    else:
        print(1, end="")
        for i in range(n-1):
            print(0, end="")