import math
inf = 10**12
def dist(i,j):
    x1,y1 = XY[i]
    x2,y2 = XY[j]
    d = (x1-x2)**2+(y1-y2)**2
    if d-int(d**0.5)**2 > 0:
        return int(d**0.5)/10*10+10
    else:
        if int(d**0.5)%10 == 0:
            return int(d**0.5)
        else:
            return int(d**0.5)/10*10+10

def dijkstra():
    d = [inf]*N
    used = [False]*N
    d[0] = 0
    while 1:
        v = -1
        for u in xrange(N):
            if not used[u] and (v == -1 or d[u] < d[v]): v = u
        if v == -1: break
        used[v] = True
        for u in xrange(N):
            d[u] = min(d[u], d[v]+D[v][u])
    return d[N-1]
    
N = int(raw_input())
XY = [map(int,raw_input().split()) for i in xrange(N)]
_D = [[dist(i,j) for i in xrange(N)] for j in xrange(N)]
dset = sorted(list(set([_D[i][j] for i in xrange(N) for j in xrange(N)])))
ans = max(dset)
l,p,r = 0,len(dset)/2,len(dset)
for loop in xrange(50):
    D = [[_D[i][j] if _D[i][j] <= dset[p] else inf for i in xrange(N)] for j in xrange(N)]
    if dijkstra() < inf:
        ans = min(ans,dset[p])
        r = p
    else:
        l = p
    p = (r+l)/2
print ans