/**
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
*/
#include <cstring>
#include <vector>
#include <list>
#include <map>
#include <set>
#include <deque>
#include <stack>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <queue>
#include <cmath>
#include <cstdlib>
#include <ctime>
#include <cassert>

#define F first
#define S second
#define endl '\n'
#define deb(x) cout<<#x<<' '<<x<<endl;
#define pb push_back
#define all(x) (x).begin(), (x).end()

const long long MOD = 1e9 + 7;
const long long N = 1e6 + 228;

using namespace std;

typedef long long ll;
typedef pair<int, int> pii;

#ifdef IZI_KATKA
#define int __int64_t
#else
#define int __int64_t
#endif

long long readInt() {
    bool minus1 = false;
    long long result = 0;
    char ch;
    ch = getchar();
    while (true) {
        if (ch == '-') break;
        if (ch >= '0' && ch <= '9') break;
        ch = getchar();
    }
    if (ch == '-') minus1 = true; else result = ch-'0';
    while (true) {
        ch = getchar();
        if (ch < '0' || ch > '9') break;
        result = result*10 + (ch - '0');
    }
    if (minus1)
        return -result;
    else
        return result;
}

const double PI = acos(-1);
const int MAXN = 2e5 + 77;

int dp[MAXN];

main() {
	#ifdef IZI_KATKA
	assert(freopen("input", "r", stdin));
    assert(freopen("output", "w", stdout));
    #endif
    int x1 = readInt(), y1 = readInt();
    int x2 = readInt(), y2 = readInt();
    int n = readInt();
    vector <pii> kek;
    for (int i = 1; i <= n; i++){
        kek.pb({readInt(), readInt()});
    }
    if (x1 > x2) {
        x1 = -x1;
        x2 = -x2;
        for (pii &i : kek) i.F *= -1;
    }
    if (y1 > y2) {
        y1 = -y1;
        y2 = -y2;
        for (pii &i : kek) i.S *= -1;
    }
    vector <pair<int,int> > tochno_kek;
    for (pii i : kek) {
        if (x1 <= i.F && i.F <= x2 && y1 <= i.S && i.S <= y2) {
            tochno_kek.pb(i);
        }
    }
    vector<int> y;
    for (pii i : tochno_kek) {
        y.pb(i.S);
    }
    sort(all(y));
    y.erase(unique(all(y)), y.end());
    sort(all(tochno_kek));
    for (int i = 0; i <= n; i++) {
        dp[i] = MOD;
    }
    dp[0] = -MOD;
    int res = 0;
    for (auto i : tochno_kek) {
        int x = lower_bound(all(y), i.S) - y.begin();
        int v = lower_bound(dp, dp + n + 1, x) - dp;
        res = max(res, v);
        dp[v] = min(dp[v], x);
    }
    double ans = 1e2 * (x2 + y2 - x1 - y1) - res * (20 - 5 * PI);
    if (res == min(y2 - y1, x2 - x1) + 1) ans += 5 * PI;
    cout <<fixed << setprecision(11)<< ans << '\n';
    return 0;
}


Measured memory_bytes: 10860