x1,y1,x2,y2,d=map(int,raw_input().split())
x1 = max(x1,-d)
x2 = min(x2, d)
y1 = max(y1,-d)
y2 = min(y2, d)
def get(x):
    if x == 0:
        return [-d, d]
    if x == d or x == -d:
        return [0]
    if x>0:
        return [] if x>d else [d-x, x-d]
    else:
        return [] if x<-d else [d+x, -x-d]
def h(x, y):
    return abs(x)+abs(y)
def fix(x, y):
    return min(max(x, x1), x2), min(max(y, y1), y2)
p = []
e = get(x1)
p.extend(fix(x1, y) for y in e)
e = get(x2)
p.extend(fix(x2, y) for y in e)

e = get(y1)
p.extend(fix(x, y1) for x in e)
e = get(y2)
p.extend(fix(x, y2) for x in e)

p = list(set(p))
p = [e for e in p if h(e[0], e[1])<=d]
if len(p)==0:
    print 0
    exit(0)
x1 = min(e[0] for e in p)
x2 = max(e[0] for e in p)
y1 = min(e[1] for e in p)
y2 = max(e[1] for e in p)
ans = (x2-x1+1)*(y2-y1+1)
l = len(p)
for i in xrange(l):
    s1, t1 = p[i]
    for j in xrange(i+1, l):
        s2, t2 = p[j]
        dx = abs(s2-s1)
        dy = abs(t2-t1)
        if dx==dy and h(s1+s2, t1+t2)==2*d:
            ans -= dx*(dx+1)/2
print ans