#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ull unsigned long long 
ll ax,ay,bx,by;
ll l;

double dis(ll ax,ll ay,ll bx,ll by)
{
    ull dx=abs(ax-bx),dy=abs(ay-by);
    return sqrt(dx*dx+dy*dy);
}

int main(){
    cin >> ax >> ay >> bx >> by;
    cin >> l ;
    if(!((ay>l&&l>by)||(by>l&&l>ay)))
    { 
       if(ay>l) ay=ay-(ay-l)*2;
       else ay=ay+(l-ay)*2;
    } 
    printf("%.2lf",dis(ax,ay,bx,by));
    return 0;
}