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Límite de tiempo: 2 s Límite de memoria: 256 MB Puntuación total: 100

#20943. 牲畜排队

Estadísticas

Farmer John 每天给八头乳牛挤奶,她们的名字是 Bessie, Buttercup, Belinda, Beatrice, Bella, Blue, Betsy, Sue。

不幸的是,奶牛们很挑剔,要求挤奶顺序满足 $N$ 条约束($1 \leq N \leq 7$)。每条的形式为“$X$ 必须紧挨 $Y$ 挤奶”,即 $X$ 必须在 $Y$ 的紧前或紧后。

请帮助 Farmer John 找出满足所有约束的顺序。保证总是有解。若有多种,输出名字按字母序最先的顺序:第一头是在所有合法顺序中能排第一的奶牛里名字最小的;在第一头相同的合法顺序中,再选名字最小的第二头,依此类推。

输入格式

第一行包含 $N$。接下来 $N$ 行,每行一个形如 X must be milked beside Y 的句子描述约束,其中 $X$、$Y$ 是上面八个名字之一。

输出格式

输出 8 行,每行一头奶牛,表示满足所有约束的顺序。若有多种,输出按字母序最先的。

样例

输入格式 1

3
Buttercup must be milked beside Bella
Blue must be milked beside Bella
Sue must be milked beside Beatrice

输出格式 1

Beatrice
Sue
Belinda
Bessie
Betsy
Blue
Bella
Buttercup

题目署名:Brian Dean

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