f=lambda n:n*(n+1)/2;p,q,r,s,d=map(int,raw_input().split());a=0
if p>=0:x=[(p,r)]
elif r<=0:x=[(-r,-p)]
else:x=[(1,-p),(0,r)]
if q>=0:y=[(q,s)]
elif s<=0:y=[(-s,-q)]
else:y=[(1,-q),(0,s)]
for p,r in x:
	for q,s in y:
		if p+q>d:continue
		if r+s<=d:a+=(r-p+1)*(s-q+1);continue
 		if r+q<d:
			if p+s<d:a+=(r-p+1)*(s-q+1)-f(r-d+s)
			else:e=r-p+1;a+=f(e)+e*(d-r-q)
		else:
			if p+s<d:e=s-q+1;a+=f(e)+e*(d-s-p)
			else:a+=f(d-q-p+1)
print a