#5604. CSES2143 可达性查询
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CSES2143 可达性查询
Reachability Queries
A directed graph consists of n nodes and m edges. The edges are numbered 1,2,\dots,n. Your task is to answer q queries of the form "can you reach node b from node a?"
Input
The first input line has three integers n, m and q: the number of nodes, edges and queries. Then there are m lines describing the edges. Each line has two distinct integers a and b: there is an edge from node a to node b. Finally there are q lines describing the queries. Each line consists of two integers a and b: "can you reach node b from node a?"
Output
Print the answer for each query: either "YES" or "NO".
Constraints
\cdot 10^4$
Example
Input
4 4 3
1 2
2 3
3 1
4 3
1 3
1 4
4 1
Output
YES
NO
YES