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.par[rx] == self.par[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())

if N == 0:
    print(1)
    exit()
    
XY = [tuple(map(int, input().split())) for _ in range(N)]
uf = Unionfind(N)

for i in range(N):
    for j in range(i+1, N):
        Xi, Yi = XY[i]
        Xj, Yj = XY[j]
        
        if (Xj-Xi)**2+(Yj-Yi)**2 <=100:
            uf.unite(i, j)

ans = 2

for i in range(N):
    for j in range(i+1, N):
        if uf.is_same(i, j):
            Xi, Yi = XY[i]
            Xj, Yj = XY[j]
            ans = max(ans, ((Xj-Xi)**2+(Yj-Yi)**2)**0.5+2)

print(ans)