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Score : $200$ points

### Problem Statement

There are $A$ slimes.

Each time Snuke shouts, the slimes multiply by $K$ times.

In order to have $B$ or more slimes, at least how many times does Snuke need to shout?

### Constraints

• $1 \leq A \leq B \leq 10^9$
• $2 \leq K \leq 10^9$
• All values in input are integers.

### Input

Input is given from Standard Input in the following format:

$A$ $B$ $K$


### Sample Input 1

1 4 2


### Sample Output 1

2


We start with one slime. After Snuke's first shout, we have two slimes; after his second shout, we have four slimes. Thus, he needs to shout at least twice to have four or more slimes.

### Sample Input 2

7 7 10


### Sample Output 2

0


We have seven slimes already at the start.

### Sample Input 3

31 415926 5


### Sample Output 3

6