#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll, ll> l_l;
typedef pair<int, int> i_i;
template<class T>
inline bool chmax(T &a, T b) {
    if(a < b) {
        a = b;
        return true;
    }
    return false;
}

template<class T>
inline bool chmin(T &a, T b) {
    if(a > b) {
        a = b;
        return true;
    }
    return false;
}

#define EPS (1e-7)
#define INF (1e9)
#define PI (acos(-1))
//const ll mod = 1000000007;
ll x[2], y[2];
ll N;
ll X[200100], Y[200100];
long double ans;
struct SegmentTree {
private:
    int n;
    vector<int> node;
 
public:
    SegmentTree() {
        int sz = 200100;
        n = 1; while(n < sz) n *= 2;
        node.resize(2*n-1, -1e9);
        for(int i=0; i<sz; i++) node[i+n-1] = -1e9;
        for(int i=n-2; i>=0; i--) node[i] = max(node[2*i+1], node[2*i+2]);
    }
 
    void update(int x, int val) {
        x += (n - 1);
        node[x] = val;
        while(x > 0) {
            x = (x - 1) / 2;
            node[x] = max(node[2*x+1], node[2*x+2]);
        }
    }
    // hannkaikukann 
    int getmax(int a, int b, int k=0, int l=0, int r=-1) {
        if(r < 0) r = n;
        if(r <= a || b <= l) return -1e9;
        if(a <= l && r <= b) return node[k];
 
        int vl = getmax(a, b, 2*k+1, l, (l+r)/2);
        int vr = getmax(a, b, 2*k+2, (l+r)/2, r);
        return max(vl, vr);
    }
};


int main() {
    //cout.precision(10);
    cin.tie(0);
    ios::sync_with_stdio(false);
    for(int i = 0; i < 2; i++) {
        cin >> x[i] >> y[i];
    }
    if(x[0] > x[1]) {
        swap(x[0], x[1]);
        swap(y[0], y[1]);
    }
    ans = 100 * (abs(x[0] - x[1]) + abs(y[0] - y[1]));
    cerr << ans << endl;
    cin >> N;
    for(int i = 0; i < N; i++) {
        cin >> X[i] >> Y[i];
        if(X[i] < min(x[0], x[1]) or X[i] > max(x[0], x[1])) {
            i--;
            N--;
            continue;
        }
        if(Y[i] < min(y[0], y[1]) or Y[i] > max(y[0], y[1])) {
            i--;
            N--;
            continue;
        }
    }
    //for(int i = 0; i < N; i++) cerr << i << " " << X[i] << " " << Y[i] << endl;
    if(y[0] > y[1]) {
        y[0] *= -1;
        y[1] *= -1;
        for(int i = 0; i < N; i++) {
            Y[i] *= -1;
        }
    }
    ll delta = min(x[1] - x[0], y[1] - y[0]) + 1;
    vector<ll> cmp;
    cmp.push_back(x[0]);
    cmp.push_back(x[1]);
    for(int i = 0; i < N; i++) cmp.push_back(X[i]);
    sort(cmp.begin(), cmp.end());
    vector<i_i> v;
    for(int i = 0; i < 2; i++) {
        auto itr = lower_bound(cmp.begin(), cmp.end(), x[i]);
        x[i] = distance(cmp.begin(), itr);
        v.push_back({y[i], x[i]});
    }
    for(int i = 0; i < N; i++) {
        auto itr = lower_bound(cmp.begin(), cmp.end(), X[i]);
        X[i] = distance(cmp.begin(), itr);
        v.push_back({Y[i], X[i]});
    }
    sort(v.begin(), v.end());
    for(auto tmp : v) {
        //cerr << tmp.first << " " << tmp.second << endl;
    }
    SegmentTree seg;
    seg.update(0, 0);
    for(auto tmp : v) {
        int val = seg.getmax(0, tmp.second + 1);
        seg.update(tmp.second, val + 1);
    }
    ll interval = seg.getmax(0, 200005) - 2;
    //cerr << interval << " " << delta << endl;
    cerr << ans << endl;
    ans += interval * (5 * PI - 20);
    if(interval == delta) {
        ans -= 5 * PI - 20;
        ans += 10 * PI - 20;
    }
    cout << fixed << setprecision(30) << ans << endl;
    return 0;
}


Measured memory_bytes: 8688