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categories: Combinatorics
---

## Problems
- [Devu and Flowers](http://codeforces.com/contest/451/problem/E) [^1] [^2]
- [Cycles (Hard)](https://open.kattis.com/problems/cycleshard)

## External links
- [The Inclusion-Exclusion Principle](https://cp-algorithms.com/combinatorics/inclusion-exclusion.html)

[^1]: <http://ayurjain.blogspot.is/2016/08/principle-of-inclusion-exclusion.html>
[^2]: <http://codeforces.com/blog/entry/13181>