#[allow(unused_imports)]
use std::cmp::{Ordering};

#[allow(unused_imports)]
use std::collections::{BTreeMap, BTreeSet, BinaryHeap, HashMap, HashSet, VecDeque};

#[allow(unused_imports)]
use std::io::{stdin, stdout, BufWriter, Write};

#[allow(unused_imports)]
use std::iter::FromIterator;

#[allow(unused_macros)]
macro_rules! min {
    ($x: expr) => ($x);
    ($x: expr, $($z: expr),+) => {{
        std::cmp::min($x, min!($($z),*))
    }}
}

#[allow(unused_macros)]
macro_rules! max {
    ($x: expr) => ($x);
    ($x: expr, $($z: expr),+) => {{
        std::cmp::max($x, max!($($z),*))
    }}
}

#[allow(unused_macros)]
macro_rules! get { 
    ([$t: ty]) => { 
        { 
            let mut line = String::new(); 
            stdin().read_line(&mut line).unwrap(); 
            line.split_whitespace().map(|t|t.parse::<$t>().unwrap()).collect::<Vec<_>>()
        }
    };
    ([$t: ty];$n: expr) => {
        (0..$n).map(|_|get!([$t])).collect::<Vec<_>>()
    };
    ($t: ty) => {
        {
            let mut line = String::new();
            stdin().read_line(&mut line).unwrap();
            line.trim().parse::<$t>().unwrap()
        }
    };
    ($($t: ty),*) => {
        { 
            let mut line = String::new();
            stdin().read_line(&mut line).unwrap();
            let mut iter = line.split_whitespace();
            ($(iter.next().unwrap().parse::<$t>().unwrap(),)*)
        }
    };
    ($t: ty; $n: expr) => {
        (0..$n).map(|_|get!($t)).collect::<Vec<_>>()
    };
    ($($t: ty),*; $n: expr) => {
        (0..$n).map(|_|get!($($t),*)).collect::<Vec<_>>()
    };
}

#[allow(unused_macros)]
macro_rules! debug {
    ($($a:expr),*) => {
        #[cfg(debug_assertions)]
        writeln!(&mut std::io::stderr(), concat!("[DEBUG] ", $(stringify!($a), "={:?} "),*), $($a),*).unwrap();
    }
}

const BIG_STACK_SIZE: bool = true;

#[allow(dead_code)]
fn main() {
    use std::thread;
    if BIG_STACK_SIZE {
        thread::Builder::new()
            .stack_size(32 * 1024 * 1024)
            .name("solve".into())
            .spawn(solve)
            .unwrap()
            .join()
            .unwrap();
    } else {
        solve();
    }
}

fn dist((x,y): (usize, usize), (h,w): (usize, usize)) -> usize {
    min!(h-x-1,x,w-y-1,y)
}
fn solve() {
    let (h,w,k) = get!(usize, usize, usize);
    let a = get!(String; h).into_iter().map(|e| e.chars().collect::<Vec<_>>()).collect::<Vec<_>>();
    let dx = [0,0,1,-1];
    let dy = [1,-1,0,0];
    let mut queue = VecDeque::new();
    let mut visited = vec![vec![false; w];h];
    let mut mn = (0,0);
    for x in 0..h {
        for y in 0..w {
            if a[x][y] == 'S' {
                queue.push_back((x,y,0));
                visited[x][y] = true;
                mn = (x,y);
            }
        }
    }

    let mut flag = false;
    while let Some((x,y,depth)) = queue.pop_front() {
        if dist(mn, (h,w)) > dist((x,y), (h,w)) {
            mn = (x,y);
        }

        if depth + 1 > k {
            continue;
        }
        for i in 0..4 {
            let nx = x as isize + dx[i];
            let ny = y as isize + dy[i];
            if nx < 0 || ny < 0 {
                continue;
            }
            let nx = nx as usize;
            let ny = ny as usize;
            if nx > h-1 || ny > w-1 || visited[nx][ny] || a[nx][ny] == '#' {
                continue;
            }
            if nx == 0 || ny == 0 || nx == h-1 || ny == w-1 {
                flag = true;
            }
            queue.push_back((nx,ny,depth+1));
            visited[nx][ny] = true;
        }
    }
    if flag {
        println!("1");
        return;
    }

    println!("{}", (dist(mn, (h,w))+k-1)/k+1);
}


Measured memory_bytes: 12668