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:
#stdin.readline()
#int(stdin.readline())
#stdout.write()
#raw_input()
#map(int,raw_input().split())
#map(int,stdin.readline().split())
def main():
    n,t=map(int,stdin.readline().split())
    if n==1 and t==10:
        print -1
        exit()
    t = str(t)
    t += "0" * (n - len(t))
    print t
if __name__ == "__main__":
    from sys import stdin, stdout
    main()