AtCoder Beginner Contest 230
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Problem Statement
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Given is a permutation $P=(P_1,P_2,\ldots,P_N)$ of the integers from $1$ through $N$.
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Find the number of pairs of integers $(i,j)$ such that $1\leq i\leq j\leq N$ satisfying $GCD(i,j)\neq 1$ and $GCD(P_i,P_j)\neq 1$.
Here, for positive integers $x$ and $y$, $GCD(x,y)$ denotes the greatest common divisor of $x$ and $y$.
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Constraints
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$1 \leq N \leq 2\times 10^5$$(P_1,P_2,\ldots,P_N)$is a permutation of$(1,2,\ldots,N)$.- All values in input are integers.
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Input
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Input is given from Standard Input in the following format:
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N
P_1 P_2 \ldots P_N
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Output
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Print the answer.
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样例
Input #1
6
5 1 3 2 4 6
Output #1
6
Six pairs $(3,3)$, $(3,6)$, $(4,4)$, $(4,6)$, $(5,5)$, $(6,6)$ satisfy the condition, so $6$ should be printed.
Input #2
12
1 2 3 4 5 6 7 8 9 10 11 12
Output #2
32
题目信息
题面与样例版权归 AtCoder 及出题人所有;中文翻译由 AI 生成(CI 管线),如有出入请以原文为准。