#include <bits/stdc++.h>
using namespace std;
// #define int long long
// #define double long double
#define rep(i,a,b) for(int i=(int)(a); i<(int)(b); ++i)
#define repeq(i,a,b) for(int i=(int)(a); i<=(int)(b); ++i)
#define rrep(i,a,b) for(int i=(int)(a)-1; i>=(int)(b); --i)
#define rrepeq(i,a,b) for(int i=(int)(a); i>=(int)(b); --i)
#define ALL(a) (a).begin(), (a).end()
#define RALL(a) (a).rbegin(), (a).rend()
using ll = long long;
using vi = vector<int>;
using vl = vector<ll>;
using vb = vector<bool>;
template<typename T> using Graph = vector<vector<T>>;
template<typename T> using Spacial = vector<vector<vector<T>>>;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
template<typename T> using greater_priority_queue = priority_queue<T, vector<T>, greater<T>>;
const int MOD = 1e9+7;
const int MOD2 = 998244353;
// const double EPS = 1e-9;
const int dx[4] = {1, 0, -1, 0};
const int dy[4] = {0, 1, 0, -1};
string interval[2] = {" ", "\n"}; // {" ", "\n"}

template<typename T> struct is_plural : false_type{};
template<typename T1, typename T2> struct is_plural<pair<T1, T2>> : true_type{};
template<typename T> struct is_plural<vector<T>> : true_type{};
template<typename T> struct is_plural<complex<T>> : true_type{};
template<> struct is_plural<string> : true_type{};

template<typename T1, typename T2> istream &operator>>(istream &is, pair<T1, T2> &p) { return is >> p.first >> p.second; }
template<typename T1, typename T2> ostream &operator<<(ostream &os, const pair<T1, T2> &p) { return os << p.first << " " << p.second; }
template<typename T> istream &operator>>(istream &is, vector<T> &vec) { for(auto itr = vec.begin(); itr != vec.end(); ++itr) is >> *itr; return is; }
template<typename T> ostream &operator<<(ostream &os, const vector<T> &vec) { if(vec.empty()) return os; bool pl = is_plural<T>(); os << vec.front(); for(auto itr = ++vec.begin(); itr != vec.end(); ++itr) os << interval[pl] << *itr; return os; }

bool CoutYN(bool a, string y = "Yes", string n = "No") { cout << (a ? y : n) << "\n"; return a; }

template<typename T1, typename T2> inline bool chmax(T1 &a, T2 b) { return a < b && (a = b, true); }
template<typename T1, typename T2> inline bool chmin(T1 &a, T2 b) { return a > b && (a = b, true); }

long long modpow(int a, long long n, int mod = MOD) { long long ret = 1; do { if(n & 1) ret = ret * a % mod; a = 1LL * a * a % mod; } while(n >>= 1); return ret; }

template<typename T> T GCD(T a, T b) { return b ? GCD(b, a%b) : a; }
template<typename T> T LCM(T a, T b) { return a / GCD(a, b) * b; }

template<typename T1, typename T2> bool CompareBySecond(pair<T1, T2> a, pair<T1, T2> b) { return a.second != b.second ? a.second < b.second : a.first < b.first; }
template<typename T1, typename T2> bool CompareByInverse(pair<T1, T2> a, pair<T1, T2> b) { return a.first != b.first ? a.first < b.first : a.second > b.second; }


/* -------- <templates end> -------- */


const double PI = acos(-1);

void solve() {
  pii s, t; cin >> s >> t;
  int n; cin >> n;
  vector<pii> g;
  int xmin, ymin; tie(xmin, ymin) = s;
  int xmax, ymax; tie(xmax, ymax) = t;
  if(xmin > xmax) swap(xmin, xmax);
  if(ymin > ymax) swap(ymin, ymax);
  while(n--) {
    int x, y; cin >> x >> y;
    if(clamp(x, xmin, xmax) == x && clamp(y, ymin, ymax) == y) {
      g.emplace_back(x, y);
    }
  }

  if(s.first == t.first) {
    double ans = abs(s.second - t.second) * 100LL;
    for(auto &p : g) {
      if(p.first == s.first) {
        ans += PI * 10 - 20;
        break;
      }
    }
    cout << ans << endl;
    return;
  }

  if(s.second == t.second) {
    double ans = abs(s.first - t.first) * 100LL;
    for(auto &p : g) {
      if(p.second == s.second) {
        ans += PI * 10 - 20;
        break;
      }
    }
    cout << ans << endl;
    return;
  }

  if(s.second > t.second) swap(s, t);
  if(s.first < t.first) sort(ALL(g));
  else sort(RALL(g));

  vi dp;

  for(auto &p : g) {
    auto itr = lower_bound(ALL(dp), p.second);
    if(itr == dp.end()) {
      dp.emplace_back(p.second);
    } else {
      *itr = p.second;
    }
  }

  double ans = (abs(s.first - t.first) + abs(s.second - t.second)) * 100LL;
  ans += (PI * 5 - 20) * dp.size();
  if(min(abs(s.first - t.first), abs(s.second - t.second)) < dp.size()) {
    ans += PI * 5;
  }
  cout << ans << endl;
}


/* -------- <programs end> -------- */


signed main() {
  cin.tie(nullptr);
  ios::sync_with_stdio(false);
  cout << fixed << setprecision(10);
  solve();
  return 0;
}


Measured memory_bytes: 6608