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:
n,t=map(int, raw_input().split(" "))
p=1
k=n
o=1
if(n!=1):
    while(n-1>0):
        n=n-1
        p=p*10
else:
    p=1
if(n!=1):
    while(p%10==0):
        p=p+1
        while(p%t!=0):
            p=p+1
else:
    while(p%t!=0):
        p=p+1
while(k>0):
    k=k-1
    o=o*10
if(o-1<p):
    print(-1)
else:
    print(p)