#include <iostream>
#include <vector>
#include <cstdio>
#include <sstream>
#include <map>
#include <string>
#include <algorithm>
#include <queue>
#include <cmath>
#include <functional>
#include <set>
#include <ctime>
#include <random>
#include <chrono>
#include <cassert>
#include <tuple>
#include <utility>
using namespace std;

namespace {
  using Integer = long long; //__int128;
  template<class T, class S> istream& operator >> (istream& is, pair<T,S>& p){return is >> p.first >> p.second;}
  template<class T> istream& operator >> (istream& is, vector<T>& vec){for(T& val: vec) is >> val; return is;}
  template<class T> istream& operator ,  (istream& is, T& val){ return is >> val;}
  template<class T, class S> ostream& operator << (ostream& os, const pair<T,S>& p){return os << p.first << " " << p.second;}
  template<class T> ostream& operator << (ostream& os, const vector<T>& vec){for(size_t i=0; i<vec.size(); i++) os << vec[i] << (i==vec.size()-1?"":" "); return os;}
  template<class T> ostream& operator ,  (ostream& os, const T& val){ return os << " " << val;}

  template<class H> void print(const H& head){ cout << head; }
  template<class H, class ... T> void print(const H& head, const T& ... tail){ cout << head << " "; print(tail...); }
  template<class ... T> void println(const T& ... values){ print(values...); cout << endl; }

  template<class H> void eprint(const H& head){ cerr << head; }
  template<class H, class ... T> void eprint(const H& head, const T& ... tail){ cerr << head << " "; eprint(tail...); }
  template<class ... T> void eprintln(const T& ... values){ eprint(values...); cerr << endl; }

  class range{ Integer start_, end_, step_; public: struct range_iterator{ Integer val, step_; range_iterator(Integer v, Integer step) : val(v), step_(step) {} Integer operator * (){return val;} void operator ++ (){val += step_;} bool operator != (range_iterator& x){return step_ > 0 ? val < x.val : val > x.val;} }; range(Integer len) : start_(0), end_(len), step_(1) {} range(Integer start, Integer end) : start_(start), end_(end), step_(1) {} range(Integer start, Integer end, Integer step) : start_(start), end_(end), step_(step) {} range_iterator begin(){ return range_iterator(start_, step_); } range_iterator   end(){ return range_iterator(  end_, step_); } };

  inline string operator "" _s (const char* str, size_t size){ return move(string(str)); }
  constexpr Integer my_pow(Integer x, Integer k, Integer z=1){return k==0 ? z : k==1 ? z*x : (k&1) ? my_pow(x*x,k>>1,z*x) : my_pow(x*x,k>>1,z);}
  constexpr Integer my_pow_mod(Integer x, Integer k, Integer M, Integer z=1){return k==0 ? z%M : k==1 ? z*x%M : (k&1) ? my_pow_mod(x*x%M,k>>1,M,z*x%M) : my_pow_mod(x*x%M,k>>1,M,z);}
  constexpr unsigned long long operator "" _ten (unsigned long long value){ return my_pow(10,value); }

  inline int k_bit(Integer x, int k){return (x>>k)&1;} //0-indexed

  mt19937 mt(chrono::duration_cast<chrono::nanoseconds>(chrono::steady_clock::now().time_since_epoch()).count());

  template<class T> string join(const vector<T>& v, const string& sep){ stringstream ss; for(size_t i=0; i<v.size(); i++){ if(i>0) ss << sep; ss << v[i]; } return ss.str(); }

  inline string operator * (string s, int k){ string ret; while(k){ if(k&1) ret += s; s += s; k >>= 1; } return ret; }
}
constexpr long long mod = 9_ten + 7;

constexpr long double PI = acos(-1.0);

template<class Value = int>
class SegmentTree{
  int n;
  vector<Value> V;
  Value DEFAULT_VALUE;

  //evaluation function
  static Value default_evaluate(Value a, Value b){
    return max(a,b);
  }

  function< Value(Value, Value) > evaluate;

  //return evaluated value in [a,b)
  //T[at] covers [l,r)
  Value RangeEvaluation(int a, int b, int at, int l, int r){
    //out of range
    if(r <= a || b <= l) return DEFAULT_VALUE;
    //covered
    if(a <= l && r <= b) return V[at];

    //partially covered
    else{
      Value val_left = RangeEvaluation(a,b, at*2+1, l, (l+r)/2);
      Value val_right = RangeEvaluation(a,b, at*2+2, (l+r)/2, r);
      return evaluate(val_left, val_right);
    }
  }

 public:
  SegmentTree(int size, Value DEFAULT = 0, function< Value(Value, Value) > eval = default_evaluate){
    DEFAULT_VALUE = DEFAULT;
    evaluate = eval;
    n=1;
    while(n<size) n <<= 1;
    V = vector<Value>(2*n - 1, DEFAULT_VALUE);
  }

  void update(int at, Value new_val){
    at += n-1;
    V[at] = new_val;
    while(at>0){
      at = (at-1)/2;
      V[at] = evaluate(V[at*2 + 1], V[at*2 + 2]);
    }
  }


  //return evaluated value in [l,r)
  Value RangeEvaluation(int l, int r){
    if(l>=r) return DEFAULT_VALUE;
    if(l>=n) return DEFAULT_VALUE;
    return RangeEvaluation(l,r, 0, 0, n);
  }
};

template<class T>
vector<T> compress(vector<T> a, vector<T>& b){
  b = a;
  sort(b.begin(), b.end());
  b.erase( unique(b.begin(), b.end()), b.end());
  for(int i=0; i<a.size(); i++){
    a[i] = lower_bound(b.begin(), b.end(), a[i]) - b.begin();
  }
  return a;
}

int main(){
  pair<long long,long long> s, t;
  cin >> s,t;

  long long n;
  cin >> n;
  vector<pair<long long,long long>> f(n);
  cin >> f;

  shuffle(f.begin(), f.end(), mt);

  if(s.first > t.first && s.second > t.second ){
    swap(s,t);
  }

  // 右上へ
  if( s.first > t.first ){
    s.first *= -1;
    t.first *= -1;
    for(int i=0; i<n; i++){
      f[i].first *= -1;
    }
  }
  if( s.second > t.second ){
    s.second *= -1;
    t.second *= -1;
    for(int i=0; i<n; i++){
      f[i].second *= -1;
    }
  }
  assert( s.first <= t.first );
  assert( s.second <= t.second );

  if( s.first == t.first ){
    double ans = fabs(t.second - s.second) * 100.0;
    for(int i=0; i<n; i++){
      if( f[i].first != s.first ) continue;
      if( f[i].second < s.second ) continue;
      if( f[i].second > t.second ) continue;
      ans += 10*PI - 20;
    }
    printf("%.18f\n", ans);
    return 0;
  }

  if( s.second == t.second ){
    double ans = fabs(t.first - s.first) * 100.0;
    for(int i=0; i<n; i++){
      if( f[i].second != s.second ) continue;
      if( f[i].first < s.first ) continue;
      if( f[i].first > t.first ) continue;
      ans += 10*PI - 20;
    }
    printf("%.18f\n", ans);
    return 0;
  }

  map<long long, vector<long long>> xx;
  vector<long long> yy;
  for(int i=0; i<n; i++){
    yy.push_back( f[i].second );
    if( f[i].first < s.first || f[i].first > t.first ) continue;
    if( f[i].second < s.second || f[i].second > t.second ) continue;
    xx[ f[i].first ].push_back( i );
  }

  xx[ s.first ].push_back( -1 );
  xx[ t.first ].push_back( n );
  yy.push_back( t.second );
  yy.push_back( s.second );
  f.push_back( t );
  f.push_back( s );

  vector<long long> dict_y;
  auto y_ = compress(yy, dict_y);

  SegmentTree<long long> seg(y_.size()+1);

  auto itr = xx.begin();
  for(int i=0; i<xx.size(); i++){
    // 端以外は高々 1 つ
    for(auto idx : itr->second){
      if(idx == -1){
        assert( i==0 );
        continue;
      }
      if(idx == n ){
        assert( i==xx.size()-1 );
        continue;
      }
      int y = y_[idx];
      long long cnt = seg.RangeEvaluation(0, y+1);
      cnt++;
      long long cnt2 = seg.RangeEvaluation(y, y+1);

      seg.update( y, max(cnt,cnt2) );
    }
    itr = next(itr);
  }

  long long mx_f = seg.RangeEvaluation(0, y_[n]+1);
  long double ans = (long double)100.0 * (fabs(t.first - s.first) + fabs(t.second - s.second));
  ans += (5.0*PI - 20.0) * mx_f;

  if( (mx_f == t.first-s.first+1 || mx_f == t.second-s.second+1 ) && mx_f > 1 ){
    ans += 5*PI;
  }

  printf("%.18f\n", (double)ans);


  return 0;
}


Measured memory_bytes: 36024