#include <bits/stdc++.h>
#define int long long
#define pii pair<int,int>
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(c) (c).begin(),(c).end()
#define ZERO(a) memset(a,0,sizeof(a))
#define MINUS(a) memset(a,0xff,sizeof(a))
#define MINF(a) memset(a,0x3f,sizeof(a))
#define POW(n) (1LL<<(n))
#define IN(i,a,b) (a <= i && i <= b)
using namespace std;
template <typename T> inline bool CHMIN(T& a,T b) { if(a>b) { a=b; return 1; } return 0; }
template <typename T> inline bool CHMAX(T& a,T b) { if(a<b) { a=b; return 1; } return 0; }
template <typename T> inline void SORT(T& a) { sort(ALL(a)); }
template <typename T> inline void REV(T& a) { reverse(ALL(a)); }
template <typename T> inline void UNI(T& a) { sort(ALL(a)); a.erase(unique(ALL(a)),a.end()); }
template <typename T> inline void LB(vector<T>& v, T& a) { return *lower_bound(ALL(v),a); }
template <typename T> inline void LBP(vector<T>& v, T& a) { return lower_bound(ALL(v),a) - v.begin(); }
template <typename T> inline void UB(vector<T>& v, T& a) { return *upper_bound(ALL(v),a); }
template <typename T> inline void UBP(vector<T>& v, T& a) { return upper_bound(ALL(v),a) - v.begin(); }
template <typename T1, typename T2> ostream& operator<< (ostream& os, const pair<T1,T2>& p) { os << p.first << " " << p.second; return os; }
template <typename T1, typename T2> istream& operator>> (istream& is, pair<T1,T2>& p) { is >> p.first >> p.second; return is; }
template <typename T> ostream& operator<< (ostream& os, const vector<T>& v) { REP(i,v.size()) os << v[i] << " \n"[i+1==v.size()]; return os; }
template <typename T> istream& operator>> (istream& is, vector<T>& v) { for(T& in : v) is >> in; return is; }
template <typename T = int> vector<T> make_v(size_t a) { return vector<T>(a); }
template <typename T, typename... Ts> auto make_v(size_t a, Ts... ts) { return vector<decltype(make_v<T>(ts...))>(a,make_v<T>(ts...)); }
const int MOD = 1000000007;
const int INF = 0x3f3f3f3f3f3f3f3f;
const double EPS = 1e-10;

int dy[] = {-1,0,0,1};
int dx[] = {0,-1,1,0};
int H,W,K;
string S[810];
int sy, sx;
int dis[810][810];
int dis2[810][810];

signed main() {
  cin.tie(nullptr);
  ios::sync_with_stdio(false);
  cout << fixed << setprecision(10);

  cin >> H >> W >> K;
  REP(i,H) {
    cin >> S[i];
    REP(j,W) if (S[i][j] == 'S') sy = i, sx = j;
  }
  MINF(dis);
  dis[sy][sx] = 0;
  queue<pii> que;
  que.emplace(sy,sx);
  while (!que.empty()) {
    int y,x;
    tie(y,x) = que.front(); que.pop();
    for (int i = 0; i < 4; i++) {
      int ny = y + dy[i];
      int nx = x + dx[i];
      if (IN(ny,0,H-1) && IN(nx,0,W-1) && S[ny][nx] == '.' && dis[ny][nx] == INF) {
        dis[ny][nx] = dis[y][x] + 1;
        que.emplace(ny,nx);
      }
    }
  }
  MINF(dis2);
  REP(i,H) REP(j,W) if (dis[i][j] <= K) {
    dis2[i][j] = 0;
    que.emplace(i,j);
  }
  while (!que.empty()) {
    int y,x;
    tie(y,x) = que.front(); que.pop();
    for (int i = 0; i < 4; i++) {
      int ny = y + dy[i];
      int nx = x + dx[i];
      if (IN(ny,0,H-1) && IN(nx,0,W-1) && dis2[ny][nx] == INF) {
        dis2[ny][nx] = dis2[y][x] + 1;
        que.emplace(ny,nx);
      }
    }
  }
  int ans = INF;
  REP(i,H) {
    CHMIN(ans,(dis2[i][0]+K-1)/K+1);
    CHMIN(ans,(dis2[i][W-1]+K-1)/K+1);
  }
  REP(j,W) {
    CHMIN(ans,(dis2[0][j]+K-1)/K+1);
    CHMIN(ans,(dis2[H-1][j]+K-1)/K+1);
  }
  cout << ans << endl;

  return 0;
}

Measured memory_bytes: 21520