[USACO 2010 Jan S]Tea Time

题号：NC24713
时间限制：C/C++/Rust/Pascal 1秒，其他语言2秒
空间限制：C/C++/Rust/Pascal 32 M，其他语言64 M
64bit IO Format: %lld

题目描述

N (1 <= N <= 1000) cows, conveniently numbered 1..N all attend a tea time every day. M (1 <= M <= 2,000) unique pairs of those cows have already met before the first tea time. Pair i of these cows who have met is specified by two differing integers $A_i$ and $B_i$ (1 <= $A_i$ <= N; 1 <= $B_i$ <= N). The input never indicates that cows have met each other more than once.
At tea time, any cow i and cow j who have met a mutual friend cow k will meet sometime during that tea time and thus expand their circle of known cows.

Determine whether Q (1 <= Q <= 100) pairs of cows have met after tea times are held for long enough that no new cow meetings are occurring. Query j consists of a pair of different cows $X_j$ and $Y_j$ (1 <= $X_j$ <= N; 1 <= $Y_j$ <= N).

For example, suppose that out of cows 1 through 5, we know that 2 has met 5, 2 has met 3, and 4 has met 5; see (a) below.
   2---3           2---3            2---3
    \              |\  |            |\ /|
1    \     -->  1  | \ |    -->  1  | X |
      \            |  \|            |/ \|
   4---5           4---5            4---5
    (a)             (b)              (c)
In the first tea time, cow 2 meets cow 4, and cow 3 meets cow 5; see (b) above. In the second tea time, cow 3 meets cow 4; see (c) above.

输入描述:

* Line 1: Three space-separated integers: N, M, and Q
* Lines 2..M+1: Line i+1 contains two space-separated integers:  and 
* Lines M+2..M+Q+1: Line j+M+1 contains query j as two space-separated integers:  and

输出描述:

* Lines 1..Q: Line j should be 'Y' if the cows in the jth query have met and 'N' if they have not met.

示例1

输入

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输出

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Y
Y
N