{"problem":{"name":"Neq Neq","description":{"content":"We have $N$ balls arranged in a row, numbered $1$ to $N$ from left to right. Ball $i$ has an integer $A_i$ written on it. You can do the following operation any number of times. *   Choose three cons","description_type":"Markdown"},"platform":"AtCoder","limit":{"time_limit":2000,"memory_limit":262144},"difficulty":"None","is_remote":true,"is_sync":true,"sync_url":null,"sign":"arc128_d"},"statements":[{"statement_type":"Markdown","content":"We have $N$ balls arranged in a row, numbered $1$ to $N$ from left to right. Ball $i$ has an integer $A_i$ written on it.\nYou can do the following operation any number of times.\n\n*   Choose three consecutive balls $x, y, z$ $(1 \\leq x < y < z \\leq N$). Here, $A_x \\neq A_y$ and $A_y \\neq A_z$ must hold. Then, eat Ball $y$. After this operation, Balls $x$ and $z$ are considered adjacent.\n\nFind the number of possible sets of balls remaining in the end, modulo $998244353$.\n\n## Constraints\n\n*   $2 \\leq N \\leq 200000$\n*   $1 \\leq A_i \\leq N$\n*   All values in input are integers.\n\n## Input\n\nInput is given from Standard Input in the following format:\n\n$N$\n$A_1$ $A_2$ $\\cdots$ $A_N$\n\n[samples]","is_translate":false,"language":"English"}],"meta":{"iden":"arc128_d","tags":[],"sample_group":[["4\n1 2 1 2","3\n\nThere are three possible sets of balls remaining in the end: ${1,2,3,4},{1,2,4},{1,3,4}$."],["5\n5 4 3 2 1","8\n\nDifferent sequences of operations are not distinguished if they result in the same set of balls."],["5\n1 2 3 2 1","8\n\nDifferent sets of remaining balls are distinguished even if they have the same sequence of integers written on them."],["9\n1 4 2 2 9 6 9 6 6","14"]],"created_at":"2026-03-03 11:01:14"}}