#include<bits/stdc++.h>
#define fi first
#define se second
using namespace std;
const int N=200005;
const long double pi=acos(-1);
int X1,X2,Y1,Y2,n,fx=1,fy=1,st[N],top;
pair<int,int>p[N];
int main()
{
	scanf("%d%d%d%d",&X1,&Y1,&X2,&Y2);
	if(X1>X2)
		fx=-1,X1*=-1,X2*=-1;
	if(Y1>Y2)
		fy=-1,Y1*=-1,Y2*=-1;
	scanf("%d",&n);
	for(int i=1;i<=n;i++)
	{
		scanf("%d%d",&p[i].fi,&p[i].se);
		p[i].fi*=fx,p[i].se*=fy;
		if(!(X1<=p[i].fi&&p[i].fi<=X2&&Y1<=p[i].se&&p[i].se<=Y2))n--,i--;
	}
	sort(p+1,p+1+n);
	for(int i=1;i<=n;i++)
		if(!top||p[i].se>st[top])
			st[++top]=p[i].se;
		else
			*upper_bound(st+1,st+1+top,p[i].se)=p[i].se;
	long double ans=100.0L*(X2-X1+Y2-Y1)+(pi-4)*5*top;
	if(top==min(X2-X1+1,Y2-Y1+1))ans+=pi*5;
	printf("%.20Lf\n",ans);
	return 0;
}
