A15139 | Required Length
时间限制1s
内存限制256MB
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题目描述
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?
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?
输入格式
The only line of the input contains two integers $n$ and $x$ ( $2 \le n \le 19$ ; $1 \le x < 10^{n-1}$ ).
输出格式
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.
输入输出样例
输入 #1
2 1
输出 #1
-1
输入 #2
3 2
输出 #2
4
输入 #3
13 42
输出 #3
12
In the second example, the following sequence of operations achieves the goal:
1. multiply $x$ by $2$ , so $x = 2 \cdot 2 = 4$ ;
2. multiply $x$ by $4$ , so $x = 4 \cdot 4 = 16$ ;
3. multiply $x$ by $6$ , so $x = 16 \cdot 6 = 96$ ;
4. multiply $x$ by $9$ , so $x = 96 \cdot 9 = 864$ .
1. multiply $x$ by $2$ , so $x = 2 \cdot 2 = 4$ ;
2. multiply $x$ by $4$ , so $x = 4 \cdot 4 = 16$ ;
3. multiply $x$ by $6$ , so $x = 16 \cdot 6 = 96$ ;
4. multiply $x$ by $9$ , so $x = 96 \cdot 9 = 864$ .
C++ 编辑器
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评测结果：Accepted