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:
#!/usr/bin/env python3
# 584A - Codeforces Round #324 (Div. 2) - Olesya and Rodion
# Numbers

def solve(size, divisor):
    """Returns an integer of 'size' digits that is divisible by 'divisor'."""

    # The smallest number of 'size' digits (10.....0)
    base = 10**(size - 1)

    # Remainder needed to be divisible by 'divisor'
    rem = divisor - base%divisor

    if rem == divisor:
        # Already a multiple of 'divisor'
        return base
    else:
        result = base + rem
        if result >= base * 10:
            # Number obtained is too big.
            return -1
        return result

def tests():
    """Tests solution with random cases."""

    def check(n, size, divisor):
        return (len(str(n)) == size and n%divisor == 0) or n == -1

    import random

    for _ in range(10000):
        n = random.randint(1, 100)
        t = random.randint(2, 10)
        v = solve(n, t)
        assert check(v, n, t), (v, n, t)
    print('Looks good')

if __name__ == '__main__':
    #tests()
    n, t = map(int, input().split())
    print(solve(n, t))