Codeforces 569 A Music

click here ~~

                                         ***A. Music***

inputstandard input
outputstandard output
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 test(s)
input
5 2 2
output
2
input
5 4 7
output
1
input
6 2 3
output
1

题目大意：Little Lesha 想听一首歌，
这首歌长t秒，Little Lesha 先下载了s秒，
边听边下载，每q秒可以下载q-1秒的歌，
每当播放到未下载的时候，
返回开始从头开始播放，
问Little Lesha 下载一首歌需要从头开始多少次。
解题思路：
直接上代码吧：

/*
Date : 2015-8-20

Author : ITAK

Motto :

今日的我要超越昨日的我，明日的我要胜过今日的我；
以创作出更好的代码为目标，不断地超越自己。
*/
#include <iostream>
#include <cstdio>
using namespace std;

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