小虫爬墙

<p class="MsoNormal"> <span style="font-family:宋体;">一光滑墙壁高</span><span style="font-family:Tahoma;">X</span><span style="font-family:宋体;">米，有一个小虫从墙底部向上爬，每分钟爬</span><span style="font-family:Tahoma;">Y</span><span style="font-family:宋体;">米。但每爬一分钟后都要休息一分钟，在休息期间又下滑</span><span style="font-family:Tahoma;">1</span><span style="font-family:宋体;">米</span><span style="font-family:宋体;">。编程：输入</span><span style="font-family:Tahoma;">X</span><span style="font-family:宋体;">和</span><span style="font-family:Tahoma;">Y</span><span style="font-family:宋体;">，计算该小虫最少几分钟可爬到顶端。</span><span style="font-family:Tahoma;"></span> </p> <p class="MsoNormal"> <span style="font-family:宋体;">如：</span> </p> <p class="MsoNormal"> <span style="font-family:宋体;">输入</span><span style="font-family:Tahoma;">4 2</span> </p> <p class="MsoNormal"> <span style="font-family:宋体;">输出：</span><span style="font-family:Tahoma;">5</span> </p>