#include<bits/stdc++.h>
#define ll long long
using namespace std;
int main(){
	ll l1,l2,r1,r2,k;
	cin>>l1>>l2>>r1>>r2>>k;
	if(l1>l2){
		swap(l1,l2);
		swap(r1,r2);
	}
	if(l1<=l2&&r1>=r2){
		ll now=l2-l1,now2=r2-l2+1;
		if(k<=now)cout<<l1+k-1<<endl;
		else if(k<=now+now2*2){
			k-=now;
			if(k%2==0){
				k/=2;
			}
			else k=k/2+1;
			cout<<l2+k-1<<endl;
		}
		else{
			k-=now+now2*2;
			cout<<r2+k<<endl;
		}
	}
	else if(r1>l2){
		ll now=l2-l1,now2=r1-l2+1;
		if(k<=now)cout<<l1+k-1<<endl;
		else if(k<=now+now2*2){
			k-=now;
			if(k%2==0){
				k/=2;
			}
			else k=k/2+1;
			cout<<l2+k-1<<endl;
		}
		else{
			k-=now+now2*2;
			cout<<r1+k<<endl;
		}
	}
	else{
		if(k<r1-l1+1){
			cout<<l1+k-1<<endl;
		}
		else{
			k-=r1-l1+1;
			cout<<l2+k-1<<endl;
		}
	}
	return 0;
}