// CHECKLIST
// 1) SAMPLES
// 2) MAXN, EPS, ... VALUE
// 3) CORNER CASES
// 4) MINTEST !!!!!
// 5) MAXTEST (IN CASE IF IT'S NOT OBVIOUS)
// 6) SUBMIT
#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <cstdio>
#include <numeric>
#include <cstring>
#include <ctime>
#include <cstdlib>
#include <set>
#include <map>
#include <unordered_map>
#include <unordered_set>
#include <list>
#include <cmath>
#include <bitset>
#include <cassert>
#include <queue>
#include <stack>
#include <deque>
 
  
  
using namespace std;
  
  
template<typename T1, typename T2>inline void chkmin(T1 &x, T2 y) { if (x > y) x = y; }
template<typename T1, typename T2>inline void chkmax(T1 &x, T2 y) { if (x < y) x = y; }
/** Interface */
  
inline int readChar();
template <class T = int> inline T readInt(); 
template <class T> inline void writeInt( T x, char end = 0 );
inline void writeChar( int x ); 
inline void writeWord( const char *s );
  
/** Read */
  
static const int buf_size = 4096;
  
inline int getChar() {
    static char buf[buf_size];
    static int len = 0, pos = 0;
    if (pos == len) {
        pos = 0, len = fread(buf, 1, buf_size, stdin);
    }
    if (pos == len) {
        return -1;
    }
    return buf[pos++];
}
  
inline int readChar() {
    int c = getChar();
    while (c <= 32) {
        c = getChar();
    }
    return c;
}
  
template <class T>
inline T readInt() {
    int s = 1, c = readChar();
    T x = 0;
    if (c == '-')
        s = -1, c = getChar();
    while ('0' <= c && c <= '9')
        x = x * 10 + c - '0', c = getChar();
    return s == 1 ? x : -x;
}
  
/** Write */
  
static int write_pos = 0;
static char write_buf[buf_size];
  
inline void writeChar( int x ) {
    if (write_pos == buf_size)
        fwrite(write_buf, 1, buf_size, stdout), write_pos = 0;
    write_buf[write_pos++] = x;
}
  
template <class T> 
inline void writeInt( T x, char end ) {
    if (x < 0)
        writeChar('-'), x = -x;
  
    char s[24];
    int n = 0;
    while (x || !n)
        s[n++] = '0' + x % 10, x /= 10;
    while (n--)
        writeChar(s[n]);
    if (end)
        writeChar(end);
}
  
inline void writeWord( const char *s ) {     while (*s)
writeChar(*s++); }
  
struct Flusher {
    ~Flusher() {
        if (write_pos)
            fwrite(write_buf, 1, write_pos, stdout), write_pos = 0;
    }
} flusher;


#define sz(c) (int)(c).size()
#define all(c) (c).begin(), (c).end()
#define rall(c) (c).rbegin(), (c).rend()
#define left left228
#define right right228
#define next next228
#define rank rank228
#define prev prev228
const int MAXN = 801;
const int INF = 1000000000;


int dx[4] = {0, 0, 1, -1};
int dy[4] = {1, -1, 0, 0};
int n, m, k;
string s[MAXN];
int dist[MAXN][MAXN];


int main() {
    cin >> n >> m >> k;
    for (int i = 0; i < n; i++) {
        cin >> s[i];
    }
    int stx, sty;
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            if (s[i][j] == 'S') {
                stx = i;
                sty = j;
            }
            dist[i][j] = INF;
        }
    }
    queue<pair<int, int> > q;
    q.push(make_pair(stx, sty));
    dist[stx][sty] = 0;
    while (!q.empty()) {
        pair<int, int> a = q.front();
        q.pop();
        for (int kt = 0; kt < 4; kt++) {
            int i = a.first + dx[kt];
            int j = a.second + dy[kt];
            if (i < 0 || j < 0 || i >= n || j >= m || s[i][j] == '#') {
                continue;
            }
            if (dist[i][j] == INF) {
                dist[i][j] = dist[a.first][a.second] + 1;
                q.push(make_pair(i, j));
            }
         }
    }
    int ans = INF;
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            if (i == 0 || j == 0 || i == n - 1 || j == m - 1) {
                if (dist[i][j] <= k) {
                    ans = 1;
                }
            }
        }
    }
    if (ans == 1) {
        cout << ans << '\n';
        return 0;
    }
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            if (dist[i][j] <= k) {
                dist[i][j] = 0;
                q.push(make_pair(i, j));
            } else {
                dist[i][j] = INF;
            }
        }
    }
    while (!q.empty()) {
        pair<int, int> a = q.front();
        q.pop();
        for (int kt = 0; kt < 4; kt++) {
            int i = a.first + dx[kt];
            int j = a.second + dy[kt];
            if (i < 0 || j < 0 || i >= n || j >= m) {
                continue;
            }
            if (dist[i][j] == INF) {
                dist[i][j] = dist[a.first][a.second] + 1;
                q.push(make_pair(i, j));
            }
         }
    }
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            if (i == 0 || j == 0 || i == n - 1 || j == m - 1) {
                if (dist[i][j] != INF) {
                    chkmin(ans, 1 + (dist[i][j] + k - 1) / k);
                }
            }
        }
    }
    cout << ans << '\n';
    return 0;
}


Measured memory_bytes: 3840