N = int(input())
xes = []
yes = []

for _ in range(N):
    a, b = map(float, input().split())
    xes.append(a)
    yes.append(b)

minX = min(xes) - 1
maxX = max(xes) + 1
minY = min(yes) - 1
maxY = max(yes) + 1
# print(minX, maxX, minY, maxY)
# print("I have started")
P = 2 * (maxX - minX + maxY - minY)
# print("P=", P)
# left top angle
b1 = maxY - minX
b2 = maxY - minX
check = 0
while check == 0:
    b2 -= 1
    for i in range(N):
        if yes[i] == xes[i] + b2:
            check = 1
        check = 1
P = P + (2 ** 0.5 - 2) * (b1 - b2)
# print("P=", P)
# right bottom angle
b1 = minY - maxX
b2 = b1
check = 0
while check == 0:
    b2 += 1
    for i in range(N):
        if yes[i] == xes[i] + b2:
            check = 1
        check = 1
P = P + (2 ** 0.5 - 2) * (b2 - b1)
# print("P=", P)
# right top angle
b1 = maxY - maxX
b2 = b1
check = 0
while check == 0:
    b2 -= 1
    for i in range(N):
        if yes[i] == -xes[i] + b2:
            check = 1
        check = 1
P = P + (2 ** 0.5 - 2) * (b1 - b2)
# print("P=", P)
# bottom left angle
b1 = minY - minX
b2 = b1
check = 0
while check == 0:
    b2 += 1
    for i in range(N):
        if yes[i] == -xes[i] + b2:
            check = 1
        check = 1
P = P + (2 ** 0.5 - 2) * (b2 - b1)
# print("P=", P)

print(round(P, 10))