def root(x):
    if P[x] < 0: return x
    P[x] = root(P[x])  # 経路圧縮
    return P[x]

def merge(x, y):
    x = root(x)
    y = root(y)
    if x == y: return
    if x > y: x, y = y, x
    P[x] += P[y]
    P[y] = x

def same(x, y):
    return root(x) == root(y)

N = int(input())
if N == 0:
    print(1)
    exit()

XY = [list(map(int, input().split())) for _ in range(N)]
P = [-1] * N
D = [[0] * N for _ in range(N)]
for i in range(N - 1):
    x, y = XY[i]
    for j in range(i + 1, N):
        x1, y1 = XY[j]
        d2 = (x - x1) * (x - x1) + (y - y1) * (y - y1)
        D[i][j] = d2
        if d2 <= 100:
            merge(i, j)

ans = 2
for i in range(N - 1):
    for j in range(i + 1, N):
        if same(i, j):
            ans = max(ans, D[i][j] ** 0.5 + 2)
print(ans)