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2019-07-18 02:40 UTC

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2019-07-18 05:30 UTC
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Problem F
Coverage

A cellular provider has installed $n$ towers to support their network. Each tower provides coverage in a $1\text { km}$ radius, and no two towers are closer than $1\text { km}$ to each other. The coverage region of this network is therefore the set of all points that are no more than $1\text { km}$ away from at least one tower. The provider wants as much of this region as possible to be connected, in the sense that a user at any point within a connected subregion can travel to any other point within the connected subregion without having to exit the subregion. Their current installation of towers may or may not already form a single connected region, but they have the resources to build one more tower wherever they want, including within $1\text { km}$ of an existing tower. Given that the provider is able to build one more tower, what is the maximum number of towers (including the new one) that can be included within a single connected subregion of coverage?

Input

Each input will consist of a single test case. Note that your program may be run multiple times on different inputs. The first line of input consists of a single integer $n$ ($1 \le n \le 5\, 000$) denoting the number of existing towers. Next follow $n$ lines, each with $2$ space-separated floating-point numbers $x$ and $y$ ($0 \le x, y \le 100\, 000$, at most $5$ digits after the decimal point), denoting the location of a tower in km. It is guaranteed that the optimal number of towers will not change even if the coverage radius of all the towers is increased or decreased by $10^{-6}\text { km}$.

Output

Output a single integer, denoting the maximum number of towers that can be within a single connected subregion of the network after installing one additional tower.

Sample Input 1 Sample Output 1
5
1.0 1.0
3.1 1.0
1.0 3.1
3.1 3.1
4.2 3.1
6
Sample Input 2 Sample Output 2
5
1.0 1.0
3.1 1.0
1.0 3.1
3.1 3.1
10.0 10.0
5