#![allow(unused)]
// use itertools::Itertools;
use proconio::*;
use std::{cmp::Reverse, collections::*};
const DIJ4: [(usize, usize); 4] = [(0, !0), (!0, 0), (0, 1), (1, 0)];
fn main() {
    input! {
        h: usize, w: usize,
        a: [[usize; w]; h]
    }
    let mut one_heap = BinaryHeap::new();
    let mut zero_heap = BinaryHeap::new();
    let nv = nvs(0, 0, h, w);
    for (ni, nj) in nv {
        one_heap.push(Reverse((a[ni][nj], ni, nj)));
    }
    let nv = nvs(h-1, w-1, h, w);
    for (ni, nj) in nv {
        zero_heap.push(Reverse((a[ni][nj], ni, nj)));
    }
    
    let mut seen = vec![vec![-1; w]; h];
    seen[0][0] = 1;
    seen[h-1][w-1] = 0;

    for t in 0..h*w {
        if t%2 == 0 {
            let (i, j) = {
                let (mut i, mut j) = (h, w);
                loop {
                    let Reverse((_, ti, tj)) = one_heap.pop().unwrap();
                    if seen[ti][tj] == -1 {
                        (i, j) = (ti, tj);
                        break;
                    }
                }
                (i, j)
            };
            seen[i][j] = 1;
            let nv = nvs(i, j, h, w);
            for (ni, nj) in nv {
                if seen[ni][nj] == 0 {
                    println!("{}", t+1);
                    return;
                }
                if seen[ni][nj] == -1 {
                    one_heap.push(Reverse((a[ni][nj], ni, nj)));
                }
            }
        }
        else {
            let (i, j) = {
                let (mut i, mut j) = (h, w);
                loop {
                    let Reverse((_, ti, tj)) = zero_heap.pop().unwrap();
                    if seen[ti][tj] == -1 {
                        (i, j) = (ti, tj);
                        break;
                    }
                }
                (i, j)
            };
            seen[i][j] = 0;
            let nv = nvs(i, j, h, w);
            for (ni, nj) in nv {
                if seen[ni][nj] == 1 {
                    println!("{}", t+1);
                    return;
                }
                if seen[ni][nj] == -1 {
                    zero_heap.push(Reverse((a[ni][nj], ni, nj)));
                }
            }
        }
    }
}

fn nvs(i: usize, j: usize, h: usize, w: usize) -> Vec<(usize, usize)> {
    let mut ret = vec![];
    for (di, dj) in DIJ4 {
        let ni = i.wrapping_add(di);
        let nj = j.wrapping_add(dj);
        if !(ni < h && nj < w) {
            continue;
        }
        ret.push((ni, nj))
    }
    ret
}