#! 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

x1, y1, x2, y2, d = gis

def f(x1,x2)
    case
    when x2 < 0
        [false, [[-x1,-x2]]]
    when x2 == 0
        [true, [[1,-x1]]]
    when x1 > 0
        [false,[[x1,x2]]]
    when x1 == 0
        [true,[[1,x2]]]
    else
        [true,[[1,-x1],[1,x2]]]
    end
end

zx, xs = f(x1,x2)
zy, ys = f(y1,y2)

c = (zx && zy) ? 1 : 0

for2p(xs, ys) {|x,y|
    lx = x[1] - x[0]
    ly = y[1] - y[0]
    m0 = x[0] + y[0]
    m1 = x[1] + y[1]
    l0 = d - m0
    case
    when d < m0
        c += 0
    when m1 <= d
        c += (lx + 1) * (ly + 1)
    when l0 <= lx && l0 <= ly
        c += nsum(l0 + 1)
    when l0 <= lx # && ly < l0
        c += nsum(l0 + 1) - nsum(lx - ly + 1)
    when l0 <= ly # && lx < l0
        c += nsum(l0 + 1) - nsum(ly - lx + 1)
    else
        c += nsum(l0 + 1) - nsum(l0 - lx + 1) - nsum(l0 - ly + 1)
    end
}

[[zx,ys], [zy,xs]].each do |z, zs|
    next if !z
    zs.each do |e0,e1|
        case
        when e1 < d
            c += e1 - e0 + 1
        when e0 <= d && d <= e1
            c += d - e0 + 1
        end
    end
end

puts c