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 PYTHON):

Solution:
import os
import sys
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()))

input = lambda: sys.stdin.readline().rstrip('\r\n')

# ref. https://codeforces.com/blog/entry/71884
# 1) inp(), For taking integer inputs.
# 2) inlt(), For taking List inputs.
# 3) insr(), For taking string inputs. 
#           Actually it returns a List of Characters, 
#           instead of a string, which is easier to use in Python, 
#           because in Python, Strings are Immutable.
# 4) invr(), For taking space seperated integer variable inputs.

def inp():
    return(int(input()))
def inlt():
    return(list(map(int,input().split())))
def insr():
    s = input()
    return(list(s[:len(s)]))
def invr():
    return(map(int,input().split()))

n, t = inlt()

if n == 1 and t == 10:
    sys.stdout.write(str(-1) + '\n')
else:
    sys.stdout.write(str(t))
    while n > 2:
        sys.stdout.write(str(0))
        n-=1
    
    if n >=2 and t < 10:
        sys.stdout.write(str(0) + '\n')