{"problem":{"name":"C. Polar map","description":{"content":"See PDF statement in attachment. ","description_type":"Markdown"},"platform":"Codeforces","limit":{"time_limit":8000,"memory_limit":262144},"difficulty":"None","is_remote":true,"is_sync":true,"sync_url":null,"sign":"CF10179C"},"statements":[{"statement_type":"Markdown","content":"See PDF statement in attachment.\n\n[samples]","is_translate":false,"language":"English"},{"statement_type":"Markdown","content":"**Definitions**  \nLet $ n \\in \\mathbb{Z}^+ $ be the number of nodes.  \nLet $ A = (a_1, a_2, \\dots, a_n) $ be a permutation of $ \\{1, 2, \\dots, n\\} $, where $ a_i $ denotes the parent of node $ i $ (with $ a_i = i $ indicating a root).\n\n**Constraints**  \n1. $ 1 \\leq n \\leq 2 \\times 10^6 $  \n2. $ a_i \\in \\{1, 2, \\dots, n\\} $ for all $ i \\in \\{1, \\dots, n\\} $  \n3. All $ a_i $ are distinct.\n\n**Objective**  \nCompute the number of roots in the forest, i.e., the number of nodes $ i $ such that $ a_i = i $.","is_translate":false,"language":"Formal"}],"meta":{"iden":"CF10179C","tags":[],"sample_group":[],"created_at":"2026-03-03 11:00:39"}}