#include <bits/stdc++.h>
#define GET_MACRO(a, b, c, NAME, ...) NAME
#define rep(...) GET_MACRO(__VA_ARGS__, rep3, rep2)(__VA_ARGS__)
#define rep2(i, a) rep3 (i, 0, a)
#define rep3(i, a, b) for (int i = (a); i < (b); i++)
#define repr(...) GET_MACRO(__VA_ARGS__, repr3, repr2)(__VA_ARGS__)
#define repr2(i, a) repr3 (i, 0, a)
#define repr3(i, a, b) for (int i = (b) - 1; i >= (a); i--)
template<class T1, class T2> inline bool chmin(T1 &a, T2 b) { return b < a && (a = b, true); }
template<class T1, class T2> inline bool chmax(T1 &a, T2 b) { return a < b && (a = b, true); }
using namespace std;
typedef long long ll;

typedef __int128_t D;
typedef complex<D> P;
const D eps = 0;

/*/
D abs(D a) {
	if (a < 0) return -a;
	return a;
}
/*/

D dot(P a, P b) {
	return real(conj(a) * b);
}

D cross(P a, P b) {
	return imag(conj(a) * b);
}

bool comp(P a, P b) {
	if (a.real() != b.real()) return a.real() < b.real();
	return a.imag() < b.imag();
}

vector<P> convexfull(vector<P> &ps) {
	int n = ps.size();
	sort(ps.begin(), ps.end(), comp);
	int k = 0;
	vector<P> qs(n * 2);
	for (int i = 0; i < n; i++) {
		while (k > 1 && cross(qs[k - 1] - qs[k - 2], ps[i] - qs[k - 1]) <= 0) k--;
		qs[k++] = ps[i];
	}
	for (int i = n - 2, t = k; i >= 0; i--) {
		while (k > t && cross(qs[k - 1] - qs[k - 2], ps[i] - qs[k - 1]) <= 0) k--;
		qs[k++] = ps[i];
	}
	qs.resize(k - 1);
	return qs;
}

int ccw(P a, P b, P c) {
	b -= a; c -= a;
	if (cross(b, c) > eps) return 1;
	if (cross(b, c) < -eps) return -1;
	if (dot(b, c) < -eps) return 2;
	if (norm(b) < norm(c)) return -2;
	return 0;
}

bool intersectSS(P p1, P p2, P p3, P p4) {
	return ccw(p1, p2, p3) * ccw(p1, p2, p4) <= 0 &&
	ccw(p3, p4, p1) * ccw(p3, p4, p2) <= 0;
}

P intersection(P p1, P p2, P q1, P q2) {
	P base = q2 - q1;
	D d1 = abs(cross(base, p1 - q1));
	D d2 = abs(cross(base, p2 - q1));
	return p1 + (p2 - p1) * d1 / (d1 + d2);
}

bool contains(P p, vector<P> poly) {
	int n = poly.size();
	int count = 0;
	rep (i, n) {
		P d = poly[(i + 1) % n] - poly[i];
		P x = p - poly[i];
		if (cross(d, x) >= 0) count++;
	}
	return count == n;
}

D area2(vector<P> ps) {
	if (ps.size() <= 2) return 0;
	int n = ps.size();
	D res = 0;
	rep (i, n) {
		P p = ps[i];
		P q = ps[(i + 1) % n];
		res += cross(p, q);
	}
	return res;
}

D lattice(P p, P q) {
	D dx = abs(real(p) - real(q));
	D dy = abs(imag(p) - imag(q));
	return __gcd(dx, dy);
}

int main() {
	D x1, y1, x2, y2, d;
	ll x1_, y1_, x2_, y2_, d_;
	cin >> x1_ >> y1_ >> x2_ >> y2_ >> d_;
	x1 = x1_;
	y1 = y1_;
	x2 = x2_;
	y2 = y2_;
	d = d_;

	if (d == 0) {
		if (x1 <= 0 && 0 <= x2 && y1 <= 0 && 0 <= y2) {
			cout << 1 << endl;
		} else {
			cout << 0 << endl;
		}
		return 0;
	}

	vector<P> ps;

	vector<P> rect;
	rect.push_back(P(x1, y1));
	rect.push_back(P(x2, y1));
	rect.push_back(P(x2, y2));
	rect.push_back(P(x1, y2));

	vector<pair<P, P>> segs;
	segs.emplace_back(P(x1, y1), P(x2, y1));
	segs.emplace_back(P(x2, y1), P(x2, y2));
	segs.emplace_back(P(x2, y2), P(x1, y2));
	segs.emplace_back(P(x1, y2), P(x1, y1));

	vector<pair<P, P>> lines;
	lines.emplace_back(P(d, 0), P(0, d));
	lines.emplace_back(P(0, d), P(-d, 0));
	lines.emplace_back(P(-d, 0), P(0, -d));
	lines.emplace_back(P(0, -d), P(d, 0));

	vector<P> poly;
	poly.push_back(P(d, 0));
	poly.push_back(P(0, d));
	poly.push_back(P(-d, 0));
	poly.push_back(P(0, -d));

	rep (i, rect.size()) {
		if (contains(rect[i], poly)) {
			ps.push_back(rect[i]);
		}
	}

	rep (i, poly.size()) {
		if (contains(poly[i], rect)) {
			ps.push_back(poly[i]);
		}
	}

	rep (i, segs.size()) {
		rep (j, lines.size()) {
			P p1 = segs[i].first;
			P p2 = segs[i].second;
			P q1 = lines[j].first;
			P q2 = lines[j].second;
			if (intersectSS(p1, p2, q1, q2)) {
				ps.emplace_back(intersection(p1, p2, q1, q2));
			}
		}
	}

	if (ps.size() == 0) {
		cout << 0 << endl;
		return 0;
	}

	set<pair<D, D>> st;
	rep (i, ps.size()) {
		st.emplace(real(ps[i]), imag(ps[i]));
	}
	ps.clear();
	for (auto p : st) {
		ps.push_back(P(p.first, p.second));
	}

	ps = convexfull(ps);
	D S = area2(ps);

	D b = 0;
	rep (i, ps.size()) {
		P p = ps[i];
		P q = ps[(i + 1) % ps.size()];
		b += lattice(p, q);
	}

	D inner = (S - b + 2) / 2;
	D ans = inner + b;
	cout << (ll)ans << endl;
	return 0;
}