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Time Limit: 2 s Memory Limit: 256 MB Total points: 100

#22321. 哦,这些滚轮

Statistics

Farmer John 安装了一台新绞盘,使他把干草捆吊进牛棚时更省力。它由 Rube Goldberg Winch Company 制造,滚轮多得令人摸不着头脑。绞盘有一块巨大钢板,上面装着许多滚轮;动力最终来自主动滚轮,FJ 将其位置记为原点 $(0,0)$。它带动另一个滚轮,后者又带动下一个,如此继续直到末端滚轮。FJ 正在寻找末端滚轮,想知道究竟是哪一个。

download.php?type=attachments&id=2917&r=0

FJ 记录了每个滚轮的坐标 $x_{i}$、$y_{i}$ $(-5,000 \le x_{i} \le 5,000; -5,000 \le y_{i} \le 5,000)$ 和半径 $r_{i}$ $(3 \le r_{i} \le 1024)$,共有 $N$ $(2 \le N \le 1080)$ 个滚轮。告诉他传动链末端滚轮的 $x,y$ 坐标(它被带动,却不带动其他滚轮)。除主动滚轮外,每个滚轮恰好由另一个滚轮带动。

输入格式

  • 第 1 行:单个整数 $N$。
  • 第 $2,\ldots,N+1$ 行:第 $i+1$ 行用三个空格分隔的整数 $x_{i}$、$y_{i}$ 和 $r_{i}$ 描述滚轮 $i$。

输出格式

  • 第 1 行:一行两个空格分隔的整数,分别为传动链末端滚轮的 $x,y$ 坐标。

样例

输入格式 1

3
0 0 30
30 40 20
-15 100 55

输出格式 1

-15 100

说明

共有三个滚轮。第一个在原点,半径 30;它带动位于 $(30,40)$、半径 20 的滚轮;后者又带动位于 $(-15,100)$、半径 55 的第三个滚轮。

题目作者:Rob Kolstad,2008

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