from heapq import heappop as hpop, heappush as hpush
from decimal import Decimal
MAX = 2*10**9
def dijkstra (s, t, L, n):
	d = [MAX for i in range(n)]
	Q = list()
	d[s] = 0
	hpush(Q,(0,s))
	while Q:
		tmp = hpop(Q)
		for v in L[tmp[1]]:
			tmpd = max(tmp[0],v[0])
			if tmpd < d[v[1]]:
				d[v[1]] = tmpd
				hpush(Q, (tmpd,v[1]))
	return d[t]
def dist(p1, p2):
	d = (Decimal((p1[0] - p2[0])**2) + Decimal((p1[1] - p2[1])**2)).sqrt()
	return int(d) + 1 if d - int(d) > 0 else int(d)

N = int(raw_input())
xy = [map(int,raw_input().split()) for i in xrange(N)]
l = [[(dist(xy[i],xy[j]),j) for j in xrange(N)] for i in xrange(N)]
print (dijkstra(0,N-1,l,N)+9) / 10 * 10