import sys
import math
import bisect
from heapq import heapify, heappop, heappush
from collections import deque, defaultdict, Counter
from functools import lru_cache
from itertools import accumulate, combinations, permutations, product

sys.setrecursionlimit(1000000)
MOD = 10 ** 9 + 7
MOD99 = 998244353

input = lambda: sys.stdin.readline().strip()
NI = lambda: int(input())
NMI = lambda: map(int, input().split())
NLI = lambda: list(NMI())
SI = lambda: input()
SMI = lambda: input().split()
SLI = lambda: list(SMI())
EI = lambda m: [NLI() for _ in range(m)]

from collections import defaultdict


class UnionFind:
    def __init__(self, n):
        # 親要素のノード番号を格納　xが根のとき-(サイズ)を格納
        self.par = [-1 for i in range(n)]
        self.n = n
        self.roots = set(range(n))
        self.group_num = n
        self.members = defaultdict(set)

        for i in range(n):
            self.members[i].add(i)

    def find(self, x):
        # 根ならその番号を返す
        if self.par[x] < 0:
            return x
        else:
            # 親の親は親
            self.par[x] = self.find(self.par[x])
            return self.par[x]

    def is_same(self, x, y):
        # 根が同じならTrue
        return self.find(x) == self.find(y)

    def unite(self, x, y):
        x = self.find(x)
        y = self.find(y)
        if x == y: return

        # 木のサイズを比較し、小さいほうから大きいほうへつなぐ
        if self.par[x] > self.par[y]:
            x, y = y, x

        self.group_num -= 1
        self.roots.discard(y)
        assert self.group_num == len(self.roots)

        self.members[x] |= self.members[y]
        self.members[y] = set()

        self.par[x] += self.par[y]
        self.par[y] = x

    def size(self, x):
        return -self.par[self.find(x)]

    def get_members(self, x):
        root = self.find(x)
        return self.members[root]

    def get_roots(self):
        return self.roots

    def group_count(self):
        return len(self.roots)

    def all_group_members(self):
        return self.members

    def __repr__(self):
        return '\n'.join('{}: {}'.format(r, self.members[r]) for r in self.roots)


def main():
    N = NI()
    XY = EI(N)
    D = [[0]*N for _ in range(N)]
    for i in range(N):
        for j in range(N):
            xi, yi = XY[i]
            xj, yj = XY[j]
            d2 = (xi-xj)**2 + (yi-yj)**2
            if d2 == 0:
                D[i][j] = 0
            else:
                d = math.isqrt(d2-1) + 1
                D[i][j] = (d+9) // 10

    def judge(X):
        uf = UnionFind(N)
        for i in range(N):
            for j in range(i+1, N):
                if D[i][j] <= X:
                    uf.unite(i, j)
        return uf.is_same(0, N-1)

    ok = 10**20
    ng = 0
    while abs(ok - ng) > 1:
        X = (ok + ng) // 2
        if judge(X):
            ok = X
        else:
            ng = X

    print(ok * 10)


if __name__ == "__main__":
    main()