Solve the programming task below in a Python markdown code block.
You are given an integer $N$ and a string consisting of '+' and digits. You are asked to transform the string into a valid formula whose calculation result is smaller than or equal to $N$ by modifying some characters. Here, you replace one character with another character any number of times, and the converted string should still consist of '+' and digits. Note that leading zeros and unary positive are prohibited.

For instance, '0123+456' is assumed as invalid because leading zero is prohibited. Similarly, '+1+2' and '2++3' are also invalid as they each contain a unary expression. On the other hand, '12345', '0+1+2' and '1234+0+0' are all valid.

Your task is to find the minimum number of the replaced characters. If there is no way to make a valid formula smaller than or equal to $N$, output $-1$ instead of the number of the replaced characters.



Input

The input consists of a single test case in the following format.


$N$
$S$


The first line contains an integer $N$, which is the upper limit of the formula ($1 \leq N \leq 10^9$). The second line contains a string $S$, which consists of '+' and digits and whose length is between $1$ and $1,000$, inclusive. Note that it is not guaranteed that initially $S$ is a valid formula.

Output

Output the minimized number of the replaced characters. If there is no way to replace, output $-1$ instead.

Examples

Input

100
+123


Output

2


Input

10
+123


Output

4


Input

1
+123


Output

-1


Input

10
++1+


Output

2


Input

2000
1234++7890


Output

2