// ---------- begin input macro ----------
// reference: https://qiita.com/tanakh/items/0ba42c7ca36cd29d0ac8
macro_rules! input {
    (source = $s:expr, $($r:tt)*) => {
        let mut iter = $s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
    ($($r:tt)*) => {
        let s = {
            use std::io::Read;
            let mut s = String::new();
            std::io::stdin().read_to_string(&mut s).unwrap();
            s
        };
        let mut iter = s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
}

macro_rules! input_inner {
    ($iter:expr) => {};
    ($iter:expr, ) => {};
    ($iter:expr, $var:ident : $t:tt $($r:tt)*) => {
        let $var = read_value!($iter, $t);
        input_inner!{$iter $($r)*}
    };
}

macro_rules! read_value {
    ($iter:expr, ( $($t:tt),* )) => {
        ( $(read_value!($iter, $t)),* )
    };
    ($iter:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($iter, $t)).collect::<Vec<_>>()
    };
    ($iter:expr, chars) => {
        read_value!($iter, String).chars().collect::<Vec<char>>()
    };
    ($iter:expr, bytes) => {
        read_value!($iter, String).bytes().collect::<Vec<u8>>()
    };
    ($iter:expr, usize1) => {
        read_value!($iter, usize) - 1
    };
    ($iter:expr, $t:ty) => {
        $iter.next().unwrap().parse::<$t>().expect("Parse error")
    };
}
// ---------- end input macro ----------

use std::io::Write;
use std::collections::*;

type Map<K, V> = BTreeMap<K, V>;
type Set<T> = BTreeSet<T>;
type Deque<T> = VecDeque<T>;

fn run() {
    input! {
        h: usize,
        w: usize,
        n: usize,
        c: [[usize; w]; h],
    }
    let mut map = Map::new();
    for (i, c) in c.iter().enumerate() {
        for (j, c) in c.iter().enumerate() {
            map.entry(*c).or_insert(vec![]).push((i, j));
        }
    }
    let mut max = 1;
    let mut board = vec![vec![0; w]; h];
    for (_, pos) in map {
        let mut add = 0;
        for &(x, y) in pos.iter() {
            for &(dx, dy) in [(1, 0), (0, 1), (!0, 0), (0, !0)].iter() {
                let x = x + dx;
                let y = y + dy;
                if x < h && y < w && board[x][y] == max {
                    add = 1;
                }
            }
        }
        max += add;
        for (x, y) in pos {
            board[x][y] = max;
        }
    }
    println!("{}", max);
}

fn main() {
    run();
}