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:
#!/usr/bin/python


def magic(numList):         # [1,2,3]
    s = map(str, numList)   # ['1','2','3']
    s = ''.join(s)          # '123'
    s = int(s)              # 123
    return s

hi = raw_input()
nlist = list()
tlist = list()
space = 0
for i in range(0, len(hi)):
    if hi[i] != ' ':
        nlist.append( hi[i])
    else:
        space = i
        break
for i in range(space +1, len(hi)):
    tlist.append( hi[i])

n = magic(nlist)
t = magic(tlist)
l = list()



if t < 10:
    for i in range(0, n):
        l.append( t )
    output = magic(l)
else:
    for i in range(0, n-1):
        l.append( 1 )
    l.append( 0 )
    output = magic(l)
if n == 1 and t == 10:
    output = -1

print(output)