import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.io.IOException;
import java.io.BufferedReader;
import java.io.Reader;
import java.io.InputStreamReader;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        MyInput in = new MyInput(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        TaskC solver = new TaskC();
        solver.solve(1, in, out);
        out.close();
    }

    static class TaskC {
        public void solve(int testNumber, MyInput in, PrintWriter out) {
            int x1 = in.nextInt();
            int y1 = in.nextInt();
            int x2 = in.nextInt();
            int y2 = in.nextInt();
            int sx = 1, sy = 1;

            if (x1 > x2) {
                x1 = -x1;
                x2 = -x2;
                sx = -1;
            }
            if (y1 > y2) {
                y1 = -y1;
                y2 = -y2;
                sy = -1;
            }

            int n = in.nextInt();
            int[][] pos = new int[n][];
            int len = 0;
            for (int i = 0; i < n; i++) {
                int x = sx * in.nextInt();
                int y = sy * in.nextInt();
                if (x >= x1 && x <= x2 && y >= y1 && y <= y2) {
                    pos[len++] = new int[]{x, y,};
                }
            }
            pos = Arrays.copyOf(pos, len);
            Arrays.sort(pos, (a, b) -> a[0] - b[0]);
            n = len;
            int[] ys = new int[n];
            for (int i = 0; i < n; i++) ys[i] = pos[i][1];
            int lis = LIS(ys);
            double r = 10;
            double gain = Math.PI * r / 2 - r * 2;
            double penalty = Math.PI * r - r * 2;
            double ans = 100.0 * (y2 - y1 + x2 - x1) + lis * gain;
            if (lis == Math.min(x2 - x1, y2 - y1) + 1) {
                ans += penalty - gain;
            }
            out.printf("%.15f\n", ans);

        }

        private static int LIS(int[] ys) {
            final int n = ys.length;
            final int[] res = new int[n];
            Arrays.fill(res, Integer.MAX_VALUE);
            for (int i = 0; i < n; i++) {
                res[lowerBound(res, ys[i])] = ys[i];
            }
            return lowerBound(res, Integer.MAX_VALUE);
        }

        private static int lowerBound(final int[] xs, final int x) {
            int low = 0, high = xs.length;
            while (low < high) {
                final int mid = (low + high) / 2;
                final int cmp = xs[mid] < x ? -1 : xs[mid] == x ? 0 : 1;
                if (cmp >= 0) high = mid;
                else low = mid + 1;
            }
            return low;
        }

    }

    static class MyInput {
        private final BufferedReader in;
        private static int pos;
        private static int readLen;
        private static final char[] buffer = new char[1024 * 8];
        private static char[] str = new char[500 * 8 * 2];
        private static boolean[] isDigit = new boolean[256];
        private static boolean[] isSpace = new boolean[256];
        private static boolean[] isLineSep = new boolean[256];

        static {
            for (int i = 0; i < 10; i++) {
                isDigit['0' + i] = true;
            }
            isDigit['-'] = true;
            isSpace[' '] = isSpace['\r'] = isSpace['\n'] = isSpace['\t'] = true;
            isLineSep['\r'] = isLineSep['\n'] = true;
        }

        public MyInput(InputStream is) {
            in = new BufferedReader(new InputStreamReader(is));
        }

        public int read() {
            if (pos >= readLen) {
                pos = 0;
                try {
                    readLen = in.read(buffer);
                } catch (IOException e) {
                    throw new RuntimeException();
                }
                if (readLen <= 0) {
                    throw new MyInput.EndOfFileRuntimeException();
                }
            }
            return buffer[pos++];
        }

        public int nextInt() {
            int len = 0;
            str[len++] = nextChar();
            len = reads(len, isSpace);
            int i = 0;
            int ret = 0;
            if (str[0] == '-') {
                i = 1;
            }
            for (; i < len; i++) ret = ret * 10 + str[i] - '0';
            if (str[0] == '-') {
                ret = -ret;
            }
            return ret;
        }

        public char nextChar() {
            while (true) {
                final int c = read();
                if (!isSpace[c]) {
                    return (char) c;
                }
            }
        }

        int reads(int len, boolean[] accept) {
            try {
                while (true) {
                    final int c = read();
                    if (accept[c]) {
                        break;
                    }
                    if (str.length == len) {
                        char[] rep = new char[str.length * 3 / 2];
                        System.arraycopy(str, 0, rep, 0, str.length);
                        str = rep;
                    }
                    str[len++] = (char) c;
                }
            } catch (MyInput.EndOfFileRuntimeException e) {
            }
            return len;
        }

        static class EndOfFileRuntimeException extends RuntimeException {
        }

    }
}



Measured memory_bytes: 34324