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:
n, t = map(int,input().split())
x = pow(10,n-1)
if n == 1:
    if t!=10:
        print(t)
    else:
        print("-1")
elif n == 2:
    if t == 2 or t == 5 or t ==  10:
        print(x)
    elif t == 3 or t == 6 or t == 8 or t == 9 or t == 4 :
        print("72")
    else:
        print("14")
elif n == 3 :
    if t == 2 or t == 5 or t ==  10:
        print(x)
    elif t == 3 or t == 6 or t == 8 or t == 9 or t == 4 :
        print("144")
    else:
        print("105")
else:
    if t == 2 or t == 5 or t ==  10 or t == 4 or t == 8:
        print(x)
    elif t == 3 or t == 6 or t == 9:
        print( x + 62)
    else:
        y = x // 7
        print((y+1)*7)