#![allow(unused_imports)]
#![allow(non_snake_case)]
use std::cmp::*;
use std::collections::*;
use std::io::Write;

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

fn main() {
    let v = read_vec::<usize>();
    let (h, w, k) = (v[0], v[1], v[2]);

    let mut start_x = 0;
    let mut start_y = 0;

    let maze = (0..h)
        .map(|_| read::<String>().chars().collect::<Vec<_>>())
        .collect::<Vec<_>>();

    for i in 0..maze.len() {
        for j in 0..maze[0].len() {
            if maze[i][j] == 'S' {
                start_x = j;
                start_y = i;
            }
        }
    }

    let mut que = std::collections::VecDeque::new();
    que.push_back((start_x, start_y, k));
    let mut d = vec![vec![std::u64::MAX; maze[0].len()]; maze.len()];
    d[start_y][start_x] = 0;

    while let Some((cur_x, cur_y, step)) = que.pop_front() {
        if step == 5 {
            break;
        }
        if cur_x > 0 && maze[cur_y][cur_x - 1] != '#' && d[cur_y][cur_x - 1] == std::u64::MAX {
            d[cur_y][cur_x - 1] = d[cur_y][cur_x] + 1;
            que.push_back((cur_x - 1, cur_y, step + 1));
        }
        if cur_x < maze[0].len() - 1
            && maze[cur_y][cur_x + 1] != '#'
            && d[cur_y][cur_x + 1] == std::u64::MAX
        {
            d[cur_y][cur_x + 1] = d[cur_y][cur_x] + 1;
            que.push_back((cur_x + 1, cur_y, step + 1));
        }
        if cur_y > 0 && maze[cur_y - 1][cur_x] != '#' && d[cur_y - 1][cur_x] == std::u64::MAX {
            d[cur_y - 1][cur_x] = d[cur_y][cur_x] + 1;
            que.push_back((cur_x, cur_y - 1, step + 1));
        }
        if cur_y < maze.len() - 1
            && maze[cur_y + 1][cur_x] != '#'
            && d[cur_y + 1][cur_x] == std::u64::MAX
        {
            d[cur_y + 1][cur_x] = d[cur_y][cur_x] + 1;
            que.push_back((cur_x, cur_y + 1, step + 1));
        }
    }

    let mut min_distance = std::usize::MAX;
    for y in 0..h {
        for x in 0..w {
            if d[y][x] == std::u64::MAX {
                continue;
            }
            min_distance = min(min_distance, x);
            min_distance = min(min_distance, y);
            min_distance = min(min_distance, w - 1 - x);
            min_distance = min(min_distance, h - 1 - y);
        }
    }
    debug!(min_distance);
    println!("{:?}", 1 + (min_distance + k - 1) / k);
}

fn read<T: std::str::FromStr>() -> T {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    s.trim().parse().ok().unwrap()
}

fn read_vec<T: std::str::FromStr>() -> Vec<T> {
    read::<String>()
        .split_whitespace()
        .map(|e| e.parse().ok().unwrap())
        .collect()
}
