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)