#include <iostream>
#include <vector>
#include <map>
#include <algorithm>
using namespace std;

#define REP(i,s,e) for (i = s; i <= e; i++)
#define rep(i,n) REP (i,0,(int)(n)-1)
#define RREP(i,s,e) for (i = s; i >= e; i--)
#define rrep(i,n) RREP (i,(int)(n)-1,0)
#define INF (int)1e8
#define MOD (int)(1e9+7)

typedef long long ll;

int d;

ll sum(int x) {
    return (ll) x * (x + 1) / 2;
}

ll f(int x, int y) {
    if (x >= d && y >= d)
        return sum(d+1);
    else if (y >= d)
        return sum(d+1) - sum(d-x);
    else if (x >= d)
        return sum(d+1) - sum(d-y);
    else
        return (ll) (x+1) * (y+1) - ((x + y > d ) ? sum(x + y - d) : 0);
}

ll g(int x1, int y1, int x2, int y2) {
    if (x2 < 0)
        return g(-x2,y1,-x1,y2);
    if (y2 < 0)
        return g(x1,-y2,x2,-y1);
    if (x1 < 0)
        return g(0,y1,x2,y2) + g(0,y1,-x1,y2) - g(0,y1,0,y2);
    if (y1 < 0)
        return g(x1,0,x2,y2) + g(x1,0,x2,-y1) - g(x1,0,x2,0);
    ll ret = f(x2,y2);
    if (x1 > 0)
        ret -= f(x1-1,y2);
    if (y1 > 0)
        ret -= f(x2,y1-1);
    if (x1 > 0 && y1 > 0)
        ret += f(x1-1,y1-1);
    return ret;
}

int main(void) {
    int x1, y1, x2, y2;
    cin >> x1 >> y1 >> x2 >> y2 >> d;
    cout << g(x1,y1,x2,y2) << endl;
    return 0;
}