Problem 2928 --4.2.2 The Perfect Stall

2928: 4.2.2 The Perfect Stall

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Time Limit $1$ 秒/Second(s) Memory Limit $512$ 兆字节/Megabyte(s)
提交总数 $3$ 正确数量 $0$
裁判形式 标准裁判/Standard Judge 我的状态 尚未尝试
难度 分类标签 usaco

Description

Farmer John completed his new barn just last week, complete with all the latest milking technology. Unfortunately, due to engineering problems, all the stalls in the new barn are different. For the first week, Farmer John randomly assigned cows to stalls, but it quickly became clear that any given cow was only willing to produce milk in certain stalls. For the last week, Farmer John has been collecting data on which cows are willing to produce milk in which stalls. A stall may be only assigned to one cow, and, of course, a cow may be only assigned to one stall.

Given the preferences of the cows, compute the maximum number of milk-producing assignments of cows to stalls that is possible.


Input

Line 1:  One line with two integers, N (0 <= N <= 200) and M (0 <= M <= 200). N is the number of cows that Farmer John has and M is the number of stalls in the new barn. 
Line 2..N+1:  N lines, each corresponding to a single cow. The first integer (Si) on the line is the number of stalls that the cow is willing to produce milk in (0 <= Si <= M). The subsequent Si integers on that line are the stalls in which that cow is willing to produce milk. The stall numbers will be integers in the range (1..M), and no stall will be listed twice for a given cow.

Output

A single line with a single integer, the maximum number of milk-producing stall assignments that can be made.


Sample Input复制

5 5
2 2 5
3 2 3 4
2 1 5
3 1 2 5
1 2

Sample Output复制

4

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第一挑战 淡意的温柔 597540 2020-06-13 08:29:42

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