#include<bits/stdc++.h>
using namespace std;

#define REP(i,a,b) for(i=a;i<b;i++)
#define rep(i,n) REP(i,0,n)

#define mygc(c) (c)=getchar_unlocked()
#define mypc(c) putchar_unlocked(c)

#define ll long long
#define ull unsigned ll

void reader(int *x){int k,m=0;*x=0;for(;;){mygc(k);if(k=='-'){m=1;break;}if('0'<=k&&k<='9'){*x=k-'0';break;}}for(;;){mygc(k);if(k<'0'||k>'9')break;*x=(*x)*10+k-'0';}if(m)(*x)=-(*x);}
void reader(ll *x){int k,m=0;*x=0;for(;;){mygc(k);if(k=='-'){m=1;break;}if('0'<=k&&k<='9'){*x=k-'0';break;}}for(;;){mygc(k);if(k<'0'||k>'9')break;*x=(*x)*10+k-'0';}if(m)(*x)=-(*x);}
void reader(double *x){scanf("%lf",x);}
int reader(char c[]){int i,s=0;for(;;){mygc(i);if(i!=' '&&i!='\n'&&i!='\r'&&i!='\t'&&i!=EOF) break;}c[s++]=i;for(;;){mygc(i);if(i==' '||i=='\n'||i=='\r'||i=='\t'||i==EOF) break;c[s++]=i;}c[s]='\0';return s;}
template <class T, class S> void reader(T *x, S *y){reader(x);reader(y);}
template <class T, class S, class U> void reader(T *x, S *y, U *z){reader(x);reader(y);reader(z);}
template <class T, class S, class U, class V> void reader(T *x, S *y, U *z, V *w){reader(x);reader(y);reader(z);reader(w);}

void writer(int x, char c){int s=0,m=0;char f[10];if(x<0)m=1,x=-x;while(x)f[s++]=x%10,x/=10;if(!s)f[s++]=0;if(m)mypc('-');while(s--)mypc(f[s]+'0');mypc(c);}
void writer(ll x, char c){int s=0,m=0;char f[20];if(x<0)m=1,x=-x;while(x)f[s++]=x%10,x/=10;if(!s)f[s++]=0;if(m)mypc('-');while(s--)mypc(f[s]+'0');mypc(c);}
void writer(double x, char c){printf("%.15f",x);mypc(c);}
void writer(const char c[]){int i;for(i=0;c[i]!='\0';i++)mypc(c[i]);}
void writer(const char x[], char c){int i;for(i=0;x[i]!='\0';i++)mypc(x[i]);mypc(c);}
template<class T> void writerLn(T x){writer(x,'\n');}
template<class T, class S> void writerLn(T x, S y){writer(x,' ');writer(y,'\n');}
template<class T, class S, class U> void writerLn(T x, S y, U z){writer(x,' ');writer(y,' ');writer(z,'\n');}
template<class T> void writerArr(T x[], int n){int i;if(!n){mypc('\n');return;}rep(i,n-1)writer(x[i],' ');writer(x[n-1],'\n');}

char memarr[17000000]; void *mem = memarr;
#define MD 1000000007

ll solve(ll X, ll Y, ll D){
  if(X < Y) swap(X, Y);
  if(D >= X+Y) return (X+1)*(Y+1);
  if(D >= X) return (X+1)*(Y+1) - (X+Y-D)*(X+Y-D+1)/2;
  if(D >= Y) return Y*(Y+1)/2 + (Y+1)*(D-Y+1);
  return (D+1)*(D+2)/2;
}

ll solve2(ll X1, ll Y1, ll X2, ll Y2, ll D){
  ll res = 0;
  
  if(X1 > X2) swap(X1, X2);
  if(Y1 > Y2) swap(Y1, Y2);

  if(X1 < 0 && X2 > 0){
    return solve2(1, Y1, -X1, Y2, D) + solve2(0, Y1, X2, Y2, D);
  }
  if(Y1 < 0 && Y2 > 0){
    return solve2(X1, 1, X2, -Y1, D) + solve2(X1, 0, X2, Y2, D);
  }

  if(X1 < 0) return solve2(-X2, Y1, -X1, Y2, D);
  if(Y1 < 0) return solve2(X1, -Y2, X2, -Y1, D);

  res += solve(X2, Y2, D);
  if(X1) res -= solve(X1-1, Y2, D);
  if(Y1) res -= solve(X2, Y1-1, D);
  if(X1 && Y1) res += solve(X1-1, Y1-1, D);

  return res;
}

int main(){
  int i, j, k;
  int X1, Y1, X2, Y2, D;
  ll res = 0;

  reader(&X1,&Y1);
  reader(&X2,&Y2);
  reader(&D);

  res = solve2(X1, Y1, X2, Y2, D);

  writerLn(res);

  return 0;
}