#include<bits/stdc++.h>
using namespace std;
#define X first
#define Y second
#define mp make_pair
#define pb push_back
#define rep(i,a,n) for(int i=(a);i<=(n);++i)
#define dep(i,a,n) for(int i=(a);i>=(n);--i)
#define eps 1e-8
#define sqr(x) ((x)*(x))
#define MAX(a,b) a=max(a,b)
#define MIN(a,b) a=min(a,b)
#define SZ(x) ((int)(x).size())
#define CPY(a,b) memcpy(a,b,sizeof(a))
#define CLR(a) memset(a,0,sizeof(a))
#define POSIN(x,y) (1<=(x)&&(x)<=n&&1<=(y)&&(y)<=m)
#define all(x) (x).begin(),(x).end()
#define COUT(S,x) cout<<fixed<<setprecision(x)<<S<<endl
#define buli(x) (__builtin_popcountll(x))
#define bur0(x) (__builtin_ctzll(x))
#define bul2(x) (63-__builtin_clzll(x))
#define pw(x) ((ll(1))<<(x))
#define upmo(a,b) (((a)=((a)+(b))%mo)<0?(a)+=mo:(a))
#define mmo(a,b) (((a)=1ll*(a)*(b)%mo)<0?(a)+=mo:(a))
#define y0 y0z
#define y1 y1z
#define yn ynz
#define j0 j0z
#define j1 j1z
#define jn jnz
#define tm tmz
#ifdef LOCAL
#define debug(...) fprintf(stderr, __VA_ARGS__)
#else
#define debug(...) 
#endif
typedef long long ll;
typedef double lf;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef pair<lf,lf> pff;
typedef complex<double> CD;
const int inf=0x3f3f3f3f;
const int mo=1000000007;
inline void gn(long long&x){
	int sg=1;char c;while(((c=getchar())<'0'||c>'9')&&c!='-');c=='-'?(sg=-1,x=0):(x=c-'0');
	while((c=getchar())>='0'&&c<='9')x=x*10+c-'0';x*=sg;
}
inline void gn(int&x){long long t;gn(t);x=t;}
inline void gn(unsigned long long&x){long long t;gn(t);x=t;}
inline void gn(double&x){double t;scanf("%lf",&t);x=t;}
inline void gn(long double&x){double t;scanf("%lf",&t);x=t;}
template<class T1,class T2>inline void gn(T1&r,T2&s){gn(r),gn(s);}
template<class T1,class T2,class T3>inline void gn(T1&r,T2&s,T3&t){gn(r),gn(s),gn(t);}
template<class T1,class T2,class T3,class T4>inline void gn(T1&r,T2&s,T3&t,T4&u){gn(r),gn(s),gn(t),gn(u);}
inline void gs(char *s){scanf("%s",s);}
inline void gc(char &c){while((c=getchar())>126 || c<33);}
inline void pc(char c){putchar(c);}
const int DX[]={1,0,-1,0},DY[]={0,1,0,-1};
ll powmod(ll a,ll b) {ll res=1;a%=mo;for(;b;b>>=1){if(b&1)res=res*a%mo;a=a*a%mo;}return res;}
ll powmod(ll a,ll b,ll mo) {ll res=1;a%=mo;for(;b;b>>=1){if(b&1)res=res*a%mo;a=a*a%mo;}return res;}
ll gcd(ll a,ll b) { return b?gcd(b,a%b):a;}
//*******************************************

const lf pi=acos(-1);
const int N=511111,M=511111;
int l,m,n,t,C,x1,y1,x2,y2,x,y,tot;
pii a[N],b[N];
int bm;
map<int,int>Sx,Sy;
int T[M];
void add(int x,int k){for(int i=x;i<=m+10;i+=i&-i)MAX(T[i],k);}
int que(int x){int ans=0;for(int i=x;i;i-=i&-i)MAX(ans,T[i]);return ans;}
int main(){
#ifdef LOCAL
	freopen("C.in","r",stdin);//freopen("C.out","w",stdout);
#endif
	scanf("%d%d%d%d",&x1,&y1,&x2,&y2);
	scanf("%d",&n);
	m=0;
	rep(i,1,n){
		scanf("%d%d",&x,&y);
		int ok=0;
		if(x1<=x&&x<=x2)ok++,x=x-x1;
		else if(x1>=x&&x>=x2)ok++,x=x1-x;
		if(y1<=y&&y<=y2)ok++,y=y-y1;
		else if(y1>=y&&y>=y2)ok++,y=y1-y;
		/*
		if(x<=0||y<=0||x>=abs(x1-x2)||y>=abs(y1-y2)){
			b[++bm]=mp(x,y);
			continue;
		}
		*/
		if(ok==2)a[++m]=mp(x,y),Sx[x]=0,Sy[y]=0;
	}
	x=abs(x1-x2);y=abs(y1-y2);
	tot=1;for(auto &i:Sx)i.Y=++tot;
	tot=1;for(auto &i:Sy)i.Y=++tot;
	rep(i,1,m)a[i].X=Sx[a[i].X],a[i].Y=Sy[a[i].Y];
	sort(a+1,a+1+m);
	rep(i,1,m){
		add(a[i].Y,que(a[i].Y-1)+1);
	}
	int ans=que(m+10);
	lf res=1.0*(x+y)*100-ans*(20-pi/4*20);
	//printf("%d %d %d %.9lf\n",ans,x,y,res);
	if(ans==min(x,y)+1)res+=pi/4*20;
	printf("%.19lf\n",res);
	return 0;
}


Measured memory_bytes: 23936