#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <cmath>
using namespace std;
const int N=200010,M=99999999;
const long double pi=acos(-1.0);
int v[N];
struct Dat {
    int x,y;
    inline bool operator < (const Dat &A) const {return x<A.x;}
} g[N];
inline int gi() {
    int x=0,o=1;
    char ch=getchar();
    while(ch!='-'&&(ch<'0'||ch>'9')) ch=getchar();
    if(ch=='-') o=-1,ch=getchar();
    while(ch>='0'&&ch<='9') x=x*10+ch-'0',ch=getchar();
    return x*o;
}
int main() {
    int a,b,A,B,t=0,tp=0,n;
    cin>>a>>b>>A>>B;
    if(a>A) swap(a,A),swap(b,B);
    if(b>B) b=M-b,B=M-B,t=1;
    cin>>n;
    for(int i=1;i<=n;i++) {
	int x=gi(),y=gi();
	if(x<a||x>A) continue;
	if(t) y=M-y;
	if(y<b||y>B) continue;
	g[++tp]=(Dat){x,y};
    }
    long double ans=(A-a+B-b)*100.0;
    sort(g+1,g+1+tp);
    int k=0;
    for(int i=1;i<=tp;i++) {
	if(g[i].y>=v[k]) v[++k]=g[i].y;
	else v[lower_bound(v+1,v+1+k,g[i].y)-v]=g[i].y;
    }
    if(k==A-a+1||k==B-b+1) ans+=5*pi;
    ans+=k*(5*pi-20);
    printf("%.20Lf",ans);
    return 0;
}