#! ruby
# yukicoder My Practice
# author: Leonardone @ NEETSDKASU

def gs() gets.chomp end
def gi() gets.to_i end
def gss() gets.chomp.split end
def gis() gss.map(&:to_i) end
def nmapf(n,f) n.times.map{ __send__ f } end
def arr2d(h,w,v=0) h.times.map{[v] * w} end
def ngs(n) nmapf n,:gs end
def ngi(n) nmapf n,:gi end
def ngss(n) nmapf n,:gss end
def ngis(n) nmapf n,:gis end
def for2p(hr,wr,&pr) hr.each{|i|wr.each{|j| yield(i,j)}} end
def nsum(n) n * (n + 1) / 2 end

=begin
1) Ｄ範囲に完全内包
1.1: 軸に接しない 
3 1 10 9 100

1.2: 軸に接する
3 0 10 8 100

1.3: 軸をまたぐ
3 -1 10 7 100

1.4: 原点を含む
-3 -4 10 8 100

2) D範囲を完全内包
-10 -12 15 14 9

3) 

=end


def bruteforce(x1, y1, x2, y2, d)
    count = 0
    (y1..y2).each do |y|
        (x1..x2).each do |x|
            count += 1 if x.abs + y.abs <= d
        end
    end
    count
end

def bunkatsu(z1_,z2_)
    z1, z2 = [z1_, z2_].minmax
    z1a, z2a = [z1.abs, z2.abs].minmax
    case
    when z2 < 0
        [[z1a, z2a]]
    when z2 == 0
        [[0, 0], [1, z1a]]
    when z1 > 0
        [[z1a, z2a]]
    when z1 == 0
        [[0, 0], [1, z2a]]
    when z1 < 0 && 0 < z2
        [[0, 0], [1, z1a], [1, z2a]]
    else
        sleep 10
        []
    end
end



X1,Y1,X2,Y2,D = gis

#bf = bruteforce(X1, Y1, X2, Y2, D)
#puts "bruteforce %d" % [bf]

# 1) Ｄ範囲に完全内包
if [X1.abs, X2.abs].max + [Y1.abs, Y2.abs].max <= D
    count = (X2 - X1).abs.succ * (Y2 - Y1).abs.succ
    puts count
    exit
end

# 2) D範囲を完全内包
if X1.abs >= D && X2.abs >= D && Y1.abs >= D && Y2.abs >= D
    count = nsum(D) * 4 + 1
    puts count
    exit
end



xs = bunkatsu(X1, X2)
ys = bunkatsu(Y1, Y2)