# This solution works also for n-dimensional walks...
import sys
import math

def read_walk():
    return [map(float, sys.stdin.readline().split()) for _ in range(int(sys.stdin.readline()))]+[None]

def dot(P, Q): return sum(map(lambda (p, q): p*q, zip(P, Q)))
def sub(P, Q): return map(lambda (p, q): p-q, zip(P, Q))
def dist(P): return math.sqrt(dot(P, P))

A = iter(read_walk())
B = iter(read_walk())

a1 = next(A)
a2 = next(A)
b1 = next(B)
b2 = next(B)
ans = 1e30

while a2 is not None and b2 is not None:
    ad = dist(sub(a2, a1))
    bd = dist(sub(b2, b1))
    if ad > bd:
        (A, a1, a2, ad, B, b1, b2, bd) = (B, b1, b2, bd, A, a1, a2, ad)

    nb = map(lambda (x, y): x + (y-x)*ad/bd, zip(b1, b2))

    v0 = sub(a1, b1)
    v1 = sub(sub(a2, a1), sub(nb, b1))
        
    c0 = dot(v0, v0)
    c1 = dot(v0, v1)
    c2 = dot(v1, v1)
    t = max(0, min(1, -c1/c2)) if c2 > 1e-9 else 0
    ans = min(ans, c0 + 2*c1*t + c2*t*t)

    b1 = nb
    a1 = a2
    a2 = next(A)

print math.sqrt(ans)