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())
if(t==2):
    print(int('4'*(n-1)+'2'))
elif(t==3):
    print(int('3'*n))
elif(t==4):
    print(int('4'*n))
elif(t==5):
    print(int('5'*n))
elif(t==6):
    print(int('6'*n))
elif(t==7):
    print(int('7'*n))
elif(t==8):
    print(int('8'*n))
elif(t==9):
    print(int('9'*n))
elif(t==10):
    if(n==1):
        print('-1');
    else:
        print(int('1'*(n-1)+'0'))