use std::cmp::min;

const INF: i64 = 1 << 50;
fn main() {
    let (r, w) = (std::io::stdin(), std::io::stdout());
    let mut sc = IO::new(r.lock(), w.lock());
    let x1: i64 = sc.read();
    let y1: i64 = sc.read();
    let x2: i64 = sc.read();
    let y2: i64 = sc.read();

    let base = ((x1 - x2).abs() + (y1 - y2).abs()) as f64 * 100.0;
    let reduce = 20.0 - 5.0 * std::f64::consts::PI;

    let ((x1, y1), (x2, y2)) = if y1 > y2 {
        ((x2, y2), (x1, y1))
    } else {
        ((x1, y1), (x2, y2))
    };

    let (x1, x2, x_reversed) = if x1 > x2 {
        (-x1, -x2, true)
    } else {
        (x1, x2, false)
    };

    let mut xy = vec![];
    let n: usize = sc.read();
    for _ in 0..n {
        let x: i64 = sc.read();
        let y: i64 = sc.read();
        if y < y1 || y2 < y {
            continue;
        }

        let x = if x_reversed { -x } else { x };
        if x < x1 || x2 < x {
            continue;
        }

        xy.push((x, y));
    }

    assert!(x1 <= x2 && y1 <= y2);
    // let (x1, x2, y1, y2, xy) = if x1 == x2 {
    //     let mut xy = xy.into_iter().map(|(x, y)| (y, x)).collect::<Vec<_>>();
    //     xy.sort();
    //     (y1, y2, x1, x2, xy)
    // } else {
    //     xy.sort();
    //     (x1, x2, y1, y2, xy)
    // };

    xy.sort();
    let mut ans = vec![INF; n + 1];
    ans[0] = y1;

    for (_, y) in xy
        .into_iter()
        .skip_while(|&(x, _)| x < x1)
        .take_while(|&(x, _)| x <= x2)
    {
        match ans.binary_search(&y) {
            Ok(count) => {
                ans[count + 1] = min(ans[count + 1], y + 1);
                if count == 0 || ans[count - 1] == -1 {
                    ans[count] = -1;
                }
            }
            Err(i) => {
                assert!(i > 0);
                ans[i] = min(ans[i], y);
            }
        }
    }

    match ans.binary_search(&y2) {
        Ok(i) => {
            let ans = base - reduce * (i as f64);
            println!("{}", ans);
        }
        Err(i) => {
            assert!(i > 0);
            if ans[i - 1] == -1 {
                let ans = base - reduce * ((i - 1) as f64);
                println!("{}", ans + 10.0 * std::f64::consts::PI - 20.0);
            } else {
                let ans = base - reduce * ((i - 1) as f64);
                let h = (y1 - y2).abs();
                let w = (x1 - x2).abs();

                if i - 1 == min(h, w) as usize + 1 {
                    println!("{}", ans + 5.0 * std::f64::consts::PI);
                } else {
                    println!("{}", ans);
                }
            }
        }
    }
}

pub struct IO<R, W: std::io::Write>(R, std::io::BufWriter<W>);

impl<R: std::io::Read, W: std::io::Write> IO<R, W> {
    pub fn new(r: R, w: W) -> Self {
        IO(r, std::io::BufWriter::new(w))
    }
    pub fn write<S: ToString>(&mut self, s: S) {
        use std::io::Write;
        self.1.write(s.to_string().as_bytes()).unwrap();
    }
    pub fn read<T: std::str::FromStr>(&mut self) -> T {
        use std::io::Read;
        let buf = self
            .0
            .by_ref()
            .bytes()
            .map(|b| b.unwrap())
            .skip_while(|&b| b == b' ' || b == b'\n' || b == b'\r' || b == b'\t')
            .take_while(|&b| b != b' ' && b != b'\n' && b != b'\r' && b != b'\t')
            .collect::<Vec<_>>();
        unsafe { std::str::from_utf8_unchecked(&buf) }
            .parse()
            .ok()
            .expect("Parse error.")
    }
    pub fn vec<T: std::str::FromStr>(&mut self, n: usize) -> Vec<T> {
        (0..n).map(|_| self.read()).collect()
    }
    pub fn chars(&mut self) -> Vec<char> {
        self.read::<String>().chars().collect()
    }
}


Measured memory_bytes: 11344