#include<bits/stdc++.h>
using namespace std;
#define rep(i,n) for(ll i=0;i<n;i++)
#define repl(i,l,r) for(ll i=(l);i<(r);i++)
#define per(i,n) for(ll i=(n)-1;i>=0;i--)
#define perl(i,r,l) for(ll i=r-1;i>=l;i--)
#define fi first
#define se second
#define pb push_back
#define ins insert
#define pqueue(x) priority_queue<x,vector<x>,greater<x>>
#define all(x) (x).begin(),(x).end()
#define CST(x) cout<<fixed<<setprecision(x)
#define vtpl(x,y,z) vector<tuple<x,y,z>>
#define rev(x) reverse(x);
using ll=long long;
using vl=vector<ll>;
using vvl=vector<vector<ll>>;
using pl=pair<ll,ll>;
using vpl=vector<pl>;
using vvpl=vector<vpl>;
const ll MOD=1000000007;
const ll MOD9=998244353;
const int inf=1e9+10;
const ll INF=4e18;
//const ll dy[9]={0,1,-1,0,1,1,-1,-1,0};
//const ll dx[9]={1,0,0,-1,1,-1,1,-1,0};
template<class T> inline bool chmin(T& a, T b) {
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}
template<class T> inline bool chmax(T& a, T b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
} 

int main(){
    vl x(2),y(2);
    cin >> x[0] >> y[0] >> x[1] >> y[1];
    ll d;cin >> d;
    vl pls={y[0],y[1],d,-d,0,y[0]+1,y[1]-1,d-1,-d+1};//交点や変化点のy座標を入れる
    rep(i,2){
        pls.push_back(d-abs(x[i]));
        pls.push_back(-d+abs(x[i]));
        pls.push_back(d-abs(x[i])-1);
        pls.push_back(-d+abs(x[i])-1);
        pls.push_back(d-abs(x[i])+1);
        pls.push_back(-d+abs(x[i])+1);
    }
    sort(all(pls));pls.erase(unique(all(pls)),pls.end());
    vl np;
    for(auto ys:pls){
        if(ys<y[0]||ys>y[1]||ys<-d||ys>d)continue;
        np.push_back(ys);
    }
    vl vals;
    for(auto ys:np){
        ll lx=-d+abs(ys),rx=d-abs(ys);
        chmax(lx,x[0]);chmin(rx,x[1]);
        ll r=max(rx-lx+1,0LL);
        vals.push_back(r);
    } 
    ll ans=0;
    rep(i,np.size()-1){
        ans+=(vals[i]+vals[i+1])*(np[i+1]-np[i]+1)/2;
        ans-=vals[i+1];
    }
    cout << ans+vals.back() << endl;
}