B'You are given two integer numbers, n and x . You may perform several operations with the integer x . Each operation you perform is the following one: choose any digit y that occurs in the decimal representation of x at least once, and replace x by x cdot y . You want to make the length of decimal representation of x (without leading zeroes) equal to n . What is the minimum number of operations required to do that? The only line of the input contains two integers n and x ( 2 <= n <= 19 ; 1 <= x < 10^{n-1} ). Print one integer -- the minimum number of operations required to make the length of decimal representation of x (without leading zeroes) equal to n , or -1 if it is impossible. In the second example, the following sequence of operations achieves the goal: '...