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:
li= map(int, raw_input().split())
n = li[0]
t = li[1]

if (n == 1 and t == 10):
    print "-1"
else:
    if (t == 10):
        t = 1
    st = ""+str(t)
    for x in range(n-1):
        st += '0'
    print st

    
##if (n == 1):
##    print t,
##else :
##    if (t == 3 or t == 6 or t == 9 or t==2 or t==5 or t==10):
##        print 9,
##        for x in range(n-1):
##            print 0,
##    elif (t == 4):
##        if n == 2:
##            print 16
##        else:
##            print 1,
##            for x in range(n-1):
##                print 0,
##    
##    elif (t == 8):
##        if n == 2:
##            print 16
##        elif (n==3):
##            print 800
##        else:
##            print 1,
##            for x in range(n-1):
##                print 0,
##    elif (t == 7):