import math


def dist2(p1, p2):
    return (p1[0] - p2[0]) ** 2 + (p1[1] - p2[1]) ** 2

def md(ps, g):
    g = list(g)

    m = 0
    for i in range(len(g)):
        pi = ps[g[i]]
        for j in range(i + 1, len(g)):
            pj = ps[g[j]]
            d2 = dist2(pi, pj)
            if d2 > m:
                m = d2
    return m


def solve(n, ps):
    g = [None] * n
    gs = []

    # 相互通信できるグループに分ける。 O(n^2)
    for i in range(n):
        pi = ps[i]
        if g[i] is None:
            g[i] = {i}
            gs.append(g[i])
        for j in range(i + 1, n):
            if g[j] is not None:
                continue
            pj = ps[j]
            if dist2(pi, pj) <= 100:
                g[i].add(j)
                g[j] = g[i]

    # グループ内のアンテナの間の最大距離をグループごとに求める
    # それの最大値 + 2 が答え
    if len(gs) < 1:
        return 1
    mmd = math.sqrt(max(md(ps, g) for g in gs))
    return mmd + 2


def main():
    n = int(input())
    ps = []
    for i in range(n):
        ps.append(tuple(map(int, input().split())))

    a = solve(n, ps)
    print(a)


if __name__ == '__main__':
    main()