#![allow(unused_imports, dead_code, unused_macros, unused_variables, non_snake_case, unused_parens)]
use proconio::{input,marker::{Bytes, Chars, Usize1,Isize1}};
use std::cmp::*;
use std::mem::swap;
use std::collections::*;

const MOD:u64 = 998244353;
const INF:i64 = 0x3fff_ffff_ffff_ffff;

macro_rules! min {($a:expr $(,)*) => {{$a}};($a:expr, $b:expr $(,)*) => {{std::cmp::min($a, $b)}};($a:expr, $($rest:expr),+ $(,)*) => {{std::cmp::min($a, min!($($rest),+))}};}
macro_rules! max {($a:expr $(,)*) => {{$a}};($a:expr, $b:expr $(,)*) => {{std::cmp::max($a, $b)}};($a:expr, $($rest:expr),+ $(,)*) => {{std::cmp::max($a, max!($($rest),+))}};}
macro_rules! chmin {($base:expr, $($cmps:expr),+ $(,)*) => {{let cmp_min = min!($($cmps),+);if $base > cmp_min {$base = cmp_min;true} else {false}}};}
macro_rules! chmax {($base:expr, $($cmps:expr),+ $(,)*) => {{let cmp_max = max!($($cmps),+);if $base < cmp_max {$base = cmp_max;true} else {false}}};}
macro_rules! mulvec {($x:expr; $s:expr) => {vec![$x; $s]};($x:expr; $s0:expr; $( $s:expr );+) => {mulvec![vec![$x; $s0]; $( $s );+ ]};}
macro_rules! outputln {($var:expr)=>{println!("{}",$var)};($var:expr,$($vars:expr),+)=>{print!("{} ",$var);outputln!($($vars),+);};}
macro_rules! debug {($($a:expr),* $(,)*) => {eprintln!(concat!($("| ",stringify!($a), "={:?} "),*, "|"),$(&$a),*);};}

const DYX:[(usize,usize);4] = [(!0,0), (0,1), (1,0), (0,!0)];
fn solve() {
	input! {
		H:usize,
		W:usize,
		A:[[usize;W];H],
	}

	let mut que = vec![BinaryHeap::new();2];
	let mut field = mulvec!(-1;W;H);
	field[0][0] = 0;
	field[H-1][W-1] = 1;
	for (i, (h,w)) in [(0,0), (H-1,W-1)].into_iter().enumerate() {
		for (dw,dh) in DYX {
			let h2 = h.wrapping_add(dh);
			let w2 = w.wrapping_add(dw);
			if h2 < H && w2 < W {
				que[i].push((Reverse(A[h2][w2]),(h2,w2)));
			}
		}
	}
	let mut ans = 0;

	let mut i = 0;
	'out:while let Some((_, (h,w))) = que[i].pop() {
		if field[h][w] >= 0 {continue}
		ans += 1;
		field[h][w] = i as i32;

		for (dw,dh) in DYX {
			let h2 = h.wrapping_add(dh);
			let w2 = w.wrapping_add(dw);
			if h2 < H && w2 < W {
				if field[h2][w2] == (i^1) as i32 {
					break 'out;
				}
				if field[h2][w2] == i as i32 {
					continue;
				}
				que[i].push((Reverse(A[h2][w2]),(h2,w2)));
			}
		}
		i ^= 1;
	}

	outputln!(ans);

}

fn main() {
    std::thread::Builder::new()
        .stack_size(128 * 1024 * 1024)
        .spawn(|| solve()).unwrap()
        .join().unwrap();
}