2015 HUAS Summer Contest#5~C

Description

Little Lesha loves listening to music via his smartphone. But the smartphone doesn't have much memory, so Lesha listens to his favorite songs in a well-known social network InTalk.

Unfortunately, internet is not that fast in the city of Ekaterinozavodsk and the song takes a lot of time to download. But Lesha is quite impatient. The song's duration is T seconds. Lesha downloads the first S seconds of the song and plays it. When the playback reaches the point that has not yet been downloaded, Lesha immediately plays the song from the start (the loaded part of the song stays in his phone, and the download is continued from the same place), and it happens until the song is downloaded completely and Lesha listens to it to the end. For q seconds of real time the Internet allows you to download q - 1 seconds of the track.

Tell Lesha, for how many times he will start the song, including the very first start.

Input

The single line contains three integers T, S, q (2 ≤ q ≤ 10⁴, 1 ≤ S < T ≤ 10⁵).

Output

Print a single integer — the number of times the song will be restarted.

Sample Input

Input

5 2 2

Output

2

Input

5 4 7

Output

1

Input

6 2 3

Output

1
解题思路：题目的意思是一首歌播放需要t秒，现在已经下载了s秒，之后以每秒q的速度下载。但是需要注意的是，如果边下载边听歌网速就会慢下来，就会以每秒q-1的速度下载。

程序代码：

#include <cstdio>

int main()
{
    int t, s, q, ans=1,cur;
    scanf("%d %d %d", &t, &s, &q);
    cur=q*s;
    while(cur<t)
    {
        cur=q*cur;
        ans++;
    }
    printf("%d
",ans);
	return 0;
}