import sys
input = sys.stdin.readline
from decimal import *

class Unionfind():
    def __init__(self, n):
        self.par = [-1] * n
        self.rank = [1] * n
    
    def root(self, x):
        if self.par[x] < 0:
            return x
        
        self.par[x] = self.root(self.par[x])
        
        return self.par[x]
    
    def unite(self, x, y):
        rx, ry = self.root(x), self.root(y)
        
        if rx != ry:
            if self.rank[rx] >= self.rank[ry]:
                self.par[rx] += self.par[ry]
                self.par[ry] = rx
                
                if self.rank[rx] == self.rank[ry]:
                    self.rank[rx] += 1
            else:
                self.par[ry] += self.par[rx]
                self.par[rx] = ry
    
    def is_same(self, x, y):
        return self.root(x) == self.root(y)
    
    def count(self, x):
        return -self.par[x]
    
N = int(input())
XY = [tuple(map(int, input().split())) for _ in range(N)]
edges = []

for i in range(N):
    for j in range(i+1, N):
        Xi, Yi = XY[i]
        Xj, Yj = XY[j]
        edges.append((i, j, (Xi-Xj)**2+(Yi-Yj)**2))

edges.sort(key=lambda k: k[2])
uf = Unionfind(N)

for s, t, w in edges:
    uf.unite(s, t)
    
    if uf.is_same(0, N-1):
        ng, ok = -1, 10**11
        
        while abs(ok-ng) > 1:
            mid = (ng+ok)//2
            
            if (mid*10)**2 >= w:
                ok = mid
            else:
                ng = mid
        
        print(10*ok)
        break