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:
a,b=map(int,input().split())
x=10**(a-1)
if (a==1) and (b<10):
    print(b)
elif a==1 and b==10:
    print(-1)
elif b==9 or b==3 or b==6:
    print (x+8)
elif b==8 or b==4 or b==2:
    print (x+(8-x%8))
elif b==7:
    print (x*7)
elif b==5 or b==10:   
    print(x)
else:
    print(-1)