LINE Verda プログラミングコンテスト（AtCoder Beginner Contest 263）
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Problem Statement
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There are integers with $N$ different values written on a blackboard. The $i$-th value is $A_i$ and is written $B_i$ times.
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You may repeat the following operation as many times as possible:
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- Choose two integers
$x$and$y$written on the blackboard such that$x+y$is prime. Erase these two integers.
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Find the maximum number of times the operation can be performed.
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Constraints
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$1 \leq N \leq 100$$1 \leq A_i \leq 10^7$$1 \leq B_i \leq 10^9$- All
$A_i$are distinct. - 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
A_1 B_1
A_2 B_2
\vdots
A_N B_N翻译中…
Output
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Print the answer.
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样例
Input #1
3
3 3
2 4
6 2
Output #1
3
We have $2 + 3 = 5$, and $5$ is prime, so you can choose $2$ and $3$ to erase them, but nothing else. Since there are four $2$s and three $3$s, you can do the operation three times.
Input #2
1
1 4
Output #2
2
We have $1 + 1 = 2$, and $2$ is prime, so you can choose $1$ and $1$ to erase them. Since there are four $1$s, you can do the operation twice.
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。