import sys
read=sys.stdin.buffer.read
readline=sys.stdin.buffer.readline
readlines=sys.stdin.buffer.readlines

x1, y1, x2, y2, d=map(int, readline().split())
def solve0(x, y):
    if x>y:
        x, y=y, x
    if d<=x:
        return d*(d-1)//2
    elif d<=y:
        return d*(d-1)//2-(d-x)*(d-x-1)//2
    elif d<=x+y:
        return x*y-(x+y-d)*(x+y-d-1)//2
    else:
        return x*y
def solve(xl, xr, yl, yr):
    if xl>xr or yl>yr:
        return 0
    return solve0(xr, yr)-solve0(xl-1, yr)-solve0(xr, yl-1)+solve0(xl-1, yl-1)
ans=0
ans+=solve(max(1, x1), x2, max(1, y1), y2)
ans+=solve(max(1, -x2), -x1, max(1, y1), y2)
ans+=solve(max(1, x1), x2, max(1, -y2), -y1)
ans+=solve(max(1, -x2), -x1, max(1, -y2), -y1)
if x1<=0 and 0<=x2:
    ans+=min(d, y2)-max(-d, y1)+1
if y1<=0 and 0<=y2:
    ans+=min(d, x2)-max(-d, x1)+1
if x1<=0 and y1<=0 and x2>=0 and y2>=0:
    ans-=1
print(ans)