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A. Olesya and Rodion

time limit per test

1 secondmemory limit per test

256 megabytesinput

standard inputoutput

standard outputOlesya 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

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