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 sys import stdin, stdout
import sys
import math
def get_int(): return int(stdin.readline().strip())
def get_ints(): return map(int,stdin.readline().strip().split()) 
def get_array(): return list(map(int,stdin.readline().strip().split()))
def get_string(): return stdin.readline().strip()
def op(c): return stdout.write(c)
#from collections import defaultdict 
#for _ in range(int(stdin.readline())):
n,t=get_ints()
s="1"
for i in range(n-1):
    s+="0"
s=int(s)
while len(str(s))==n:
    if s%t==0:
        print(s)
        break
    s+=1
else:
    print(-1)