{ "name": "Inclusion-Exclusion", "order": 8, "challenges": [ { "id": "59a5801209a6acac5983b618", "title": "Counting with Venn Diagrams", "description": [ "" ], "challengeSeed": [ "" ], "tests": [ "" ] }, { "id": "59a5801209a6acac5983a981", "title": "Inclusion-Exclusion Formula", "description": [ "" ], "challengeSeed": [ "" ], "tests": [ "" ] }, { "id": "59a5801209a6acac5983a982", "title": "Restricted positions and rook polynomials", "description": [ "" ], "challengeSeed": [ "" ], "tests": [ "" ] } ] }