P3026 [USACO11OPEN] Learning Languages S
题目背景
:::error[管理组提示]{open}
本题 SPJ 缺失，故目前只应当输出第一行而不需要输出方案。详见 。
:::
题目描述
Farmer John's N (2
输入格式
\* Line 1: Two space-separated integers: N and M
\* Lines 2..N+1: Line i+1 describes the languages that cow i can speak with $(K_i)+1$ space-separated integers: $K_i$, $L_i1$,
L\_i2,...,L\_i{K\_i}.
输出格式
\* Line 1: A single integer that is the minimum number of books that FJ must purchase.
\* Lines 2..B+1: Line i+1 contains two space-separated integers: the language id # and the id # of the cow to receive book i. If multiple solutions exist, print any one.