Task Completion with Dependencies

You are given P projects. For each project, you are given its number of tasks and a number of dependency pairs. The tasks are identified by integers from 1 to T, and each dependency is a pair of integers (u, v) meaning that task u must be completed before task v can be started.

Your goal is to decide whether it is possible to complete all tasks in a project without encountering any circular dependencies. Output Yes if the tasks can be completed (i.e. the dependency graph is acyclic) and No if there is a cycle.

Note: There are no duplicate or self-dependencies.

inputFormat

The input is read from stdin and has the following format:

• The first line contains an integer P, the number of projects.
• For each project, the first line contains two integers: T (number of tasks) and M (number of dependency pairs).
• This is followed by M lines, each containing two integers u and v which represent that task u must be completed before task v.

outputFormat

For each project, print a single line to stdout:

• Yes if all tasks can be completed (i.e. the dependency graph has no cycle), or
• No if there exists a cycle.

## sample

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

Yes
No

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