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())

if b==2:
    ans=10**a-2
    print(ans)
elif b==3 or b==9:
    ans=10**a-1
    print(ans)
elif b==4:
    if a==1:
        ans=10-6
        print(ans)
    else:
        ans=10**a-4
        print(ans)
elif b==5:
    ans=10**a-5
    print(ans)
elif b==6:
    ans=10**a-4
    print(ans)
elif b==10:
    if a==1:
        print(-1)
    else:
        ans=10**(a-1)
        print(ans)
elif b==7 or b==8:
    ans=b*(10**(a-1))
    print(ans)