//set many funcs template
//Ver.20180717
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<stdbool.h>
#include<time.h>
#define inf 1072114514
#define llinf 4154118101919364364
#define mod 1000000007
#define pi 3.1415926535897932384
#define cval 100000000

int max(int a,int b){if(a>b){return a;}return b;}
int min(int a,int b){if(a<b){return a;}return b;}
int zt(int a,int b){return max(a,b)-min(a,b);}
int round(int a,int b){if((a%b)*2 >= b){return (a/b)+1;}return a/b;}
int ceil(int a,int b){if(a%b==0){return a/b;}return (a/b)+1;}
int gcd(int a,int b){int c;while(b!=0){c=a%b;a=b;b=c;}return a;}
int lcm(int a,int b){int c=gcd(a,b);a/=c;return a*b;}
int nCr(int a,int b){int i,r=1;for(i=1;i<=b;i++){r*=(a+1-i);r/=i;}return r;}
int nHr(int a,int b){return nCr(a+b-1,b);}
int fact(int a){int i,r=1;for(i=1;i<=a;i++){r*=i;}return r;}
int pow(int a,int b){int i,r=1;for(i=1;i<=b;i++){r*=a;}return r;}
int dsum(int x){int r=0;while(x){r+=(x%10);x/=10;}return r;}
int dsumb(int x,int b){int r=0;while(x){r+=(x%b);x/=b;}return r;}
int sankaku(int x){return ((1+x)*x)/2;}
long long llmax(long long a,long long b){if(a>b){return a;}return b;}
long long llmin(long long a,long long b){if(a<b){return a;}return b;}
long long llzt(long long a,long long b){return llmax(a,b)-llmin(a,b);}
long long llround(long long a,long long b){if((a%b)*2 >= b){return (a/b)+1;}return a/b;}
long long llceil(long long a,long long b){if(a%b==0){return a/b;}return (a/b)+1;}
long long llgcd(long long a,long long b){long long c;while(b!=0){c=a%b;a=b;b=c;}return a;}
long long lllcm(long long a,long long b){long long c=llgcd(a,b);a/=c;return a*b;}
long long llnCr(long long a,long long b){long long i,r=1;for(i=1;i<=b;i++){r*=(a+1-i);r/=i;}return r;}
long long llnHr(long long a,long long b){return llnCr(a+b-1,b);}
long long llfact(long long a){long long i,r=1;for(i=1;i<=a;i++){r*=i;}return r;}
long long llpow(long long a,long long b){long long i,r=1;for(i=1;i<=b;i++){r*=a;}return r;}
long long lldsum(long long x){long long r=0;while(x){r+=(x%10);x/=10;}return r;}
long long lldsumb(long long x,long long b){long long r=0;while(x){r+=(x%b);x/=b;}return r;}
long long llsankaku(long long x){return ((1+x)*x)/2;}
double dbmax(double a,double b){if(a>b){return a;}return b;}
double dbmin(double a,double b){if(a<b){return a;}return b;}
double dbzt(double a,double b){return dbmax(a,b)-dbmin(a,b);}
int sortfncsj(const void *a,const void *b){if(*(int *)a>*(int *)b){return 1;}if(*(int *)a==*(int *)b){return 0;}return -1;}
int sortfnckj(const void *a,const void *b){if(*(int *)a<*(int *)b){return 1;}if(*(int *)a==*(int *)b){return 0;}return -1;}
int llsortfncsj(const void *a,const void *b){if(*(long long *)a>*(long long *)b){return 1;}if(*(long long *)a==*(long long *)b){return 0;}return -1;}
int llsortfnckj(const void *a,const void *b){if(*(long long *)a<*(long long *)b){return 1;}if(*(long long *)a==*(long long *)b){return 0;}return -1;}
int dbsortfncsj(const void *a,const void *b){if(*(double *)a>*(double *)b){return 1;}if(*(double *)a==*(double *)b){return 0;}return -1;}
int dbsortfnckj(const void *a,const void *b){if(*(double *)a<*(double *)b){return 1;}if(*(double *)a==*(double *)b){return 0;}return -1;}
int strsortfncsj(const void *a,const void *b){return strcmp((char *)a,(char *)b);}
int strsortfnckj(const void *a,const void *b){return strcmp((char *)b,(char *)a);}

void shuffledget(int x[],int n){
    srand(time(0));
    int i,b[524288],p,c;
    for(i=0;i<n;i++){
        b[i]=i;
    }
    for(i=n;i>=1;i--){
        p=rand()%i;
        c=b[i-1];b[i-1]=b[p];b[p]=c;
    }
    for(i=0;i<n;i++){
        scanf("%d",&x[b[i]]);
    }
}

int dx4[4]={1,-1,0,0};
int dy4[4]={0,0,1,-1};
int dx8[8]={-1,-1,-1,0,0,1,1,1};
int dy8[8]={-1,0,1,-1,1,-1,0,1};

int search(int x,int a[],int n){
    int st=0,fi=n-1,te;
    while(st<=fi){
        te=(st+fi)/2;
        if(a[te]<x){st=te+1;}else{fi=te-1;}
    }
    return st;
}

typedef struct{
long long xz;
long long yz;
long long ry;
}pd;

int xzsortfnc(const void *a,const void *b){
if(((pd*)a)->xz < ((pd*)b)->xz){return -1;}
if(((pd*)a)->xz > ((pd*)b)->xz){return 1;}
return 0;
}

int yzsortfnc(const void *a,const void *b){
if(((pd*)a)->yz < ((pd*)b)->yz){return -1;}
if(((pd*)a)->yz > ((pd*)b)->yz){return 1;}
return 0;
}

long long ssize=524288;
long long stree[1048576],vd=-llinf;

void sinit(){
    long long i,j;
    for(i=0;i<2*ssize;i++){
        stree[i]=-llinf;
    }
}

void upd(long long k,long long a){
    long long i,m;
    long long ld,rd,md;
    k+=ssize-1;
    stree[k]=a;
    while(k>0){
        k=(k-1)/2;
        ld=stree[2*k+1];
        rd=stree[2*k+2];
        md=llmax(ld,rd);
        stree[k]=md;
    }
}

//calc min[a,b)
//call:k=0,l=0,r=ssize
long long query(long long a,long long b,long long k,long long l,long long r){
    long long ld,rd,md;
    long long i,lp,rp;
    if(r<=a || b<=l){return vd;}
    if(a<=l && r<=b){
        return stree[k];
    }
    else{
        ld=query(a,b,k*2+1,l,(l+r)/2);
        rd=query(a,b,k*2+2,(l+r)/2,r);
        lp=0;rp=0;
        md=llmax(ld,rd);
        return md;
    }
}

int main(void){
    sinit();
    long long i,j,n,m,k,a[524288],b,c,h,w,r=0,l,t;
    long long sx,sy,fx,fy,xf=0,yf=0;
    long long x,y,p=0;
    pd pt[524288];
    double d;
    char s[524288];
    scanf("%lld%lld",&sx,&sy);
    scanf("%lld%lld",&fx,&fy);
    if(sx>fx){
        xf=1;
        sx=cval-sx;
        fx=cval-fx;
    }
    if(sy>fy){
        yf=1;
        sy=cval-sy;
        fy=cval-fy;
    }
    scanf("%lld",&n);
    for(i=0;i<n;i++){
        scanf("%lld%lld",&x,&y);
        if(xf==1){x=cval-x;}
        if(yf==1){y=cval-y;}
        if(sx<=x && x<=fx && sy<=y && y<=fy){
            pt[p].xz=x;pt[p].yz=y;
            p++;
        }
    }
    if(sx==fx){
        d=fy-sy;d*=100;
        if(p==1){
            d-=20.0f;
            d+=10.0f*pi;
        }
        printf("%.12lf\n",d);
        return 0;
    }
    if(sy==fy){
        d=fx-sx;d*=100;
        if(p==1){
            d-=20.0f;
            d+=10.0f*pi;
        }
        printf("%.12lf\n",d);
        return 0;
    }
    d=fx-sx;
    d+=(fy-sy);
    d*=100.0f;
    if(p==0){
        printf("%.12lf\n",d);
        return 0;
    }
    qsort(pt,p,sizeof(pt[0]),yzsortfnc);
    for(i=0;i<p;i++){
        pt[i].ry=i+1;
    }
    qsort(pt,p,sizeof(pt[0]),xzsortfnc);
    upd(0,0);
    for(i=0;i<p;i++){
        w=query(0,pt[i].ry,0,0,ssize);
        upd(pt[i].ry,w+1);
    }
    r=query(0,ssize,0,0,ssize);
    h=fx-sx+1;
    w=fy-sy+1;
    if(r==llmin(h,w)){
        d-=(20.0f*r);
        d+=(5.0f*(r+1)*pi);
        printf("%.12lf\n",d);
        return 0;
    }
    else{
        d-=(20.0f*r);
        d+=(5.0f*r*pi);
        printf("%.12lf\n",d);
        return 0;
    }
    return 0;
}

Measured memory_bytes: 19756