accum = lambda n: n*(n+1)/2
x1,y1,x2,y2,d = map(int,raw_input().split())
if x1 >= 0: x = [(x1,x2)]
elif x2 <= 0: x = [(-x2,-x1)]
else: x = [(1,-x1),(0,x2)]
if y1 >= 0: y = [(y1,y2)]
elif y2 <= 0: y = [(-y2,-y1)]
else: y = [(1,-y1),(0,y2)]
ans = 0
for x1,x2 in x:
	for y1,y2 in y:
		if x1 + y1 > d: continue
		if x2 + y2 <= d: 
			ans += (x2-x1+1)*(y2-y1+1) 
			continue
		if x2 + y1 >= d:
			bx = d - y1
			if x1 + y2 >= d: 
				ans += accum(bx-x1+1);
			else:
				tx = d - y2; e = y2-y1+1
				ans += accum(e) + e * (tx-x1)
 		else:
			ry = d - x2
			if x1 + y2 >= d: 
				e = x2-x1+1
				ans += accum(e) + e * (ry-y1)
			else:
				tx = d - y2
				ans += (x2-x1+1)*(y2-y1+1) - accum(x2-tx)
print ans