#include <bits/stdc++.h>
using namespace std;
const int INF = 1e9 + 10;
const int MN = 850;
pair<int, int> q[MN * MN];
bool mk[MN][MN];
int l, r, R, C;
string s[MN];
int n, m, k;
int dist[MN][MN];
int dx[4] = {-1, 0, 0, 1};
int dy[4] = {0, -1, 1, 0};
bool valid(int tr, int tc) { return tr + 1 && tc + 1 && n - tr && m - tc; }
void bfs() {
  for (int i = 0; i < MN; ++i) fill(dist[i], dist[i] + MN, INF);
  mk[R][C] = true, dist[R][C] = 0;
  q[r++] = {R, C};
  while (l < r) {
    pair<int, int> v = q[l++];
    for (int d = 0; d < 4; ++d) {
      int tr = v.first + dx[d], tc = v.second + dy[d];
      if (valid(tr, tc) && s[tr][tc] != '#' && !mk[tr][tc]) {
        mk[tr][tc] = true;
        dist[tr][tc] = dist[v.first][v.second] + 1;
        q[R++] = {tr, tc};
      }
    }
  }
}
int F(int a) { return (a + k - 1) / k; }
int main() {
  ios_base ::sync_with_stdio(false), cin.tie(0), cout.tie(0);
  cin >> n >> m >> k;
  for (int i = 0; i < n; ++i) cin >> s[i];
  for (int i = 0; i < n; ++i)
    for (int j = 0; j < m; ++j)
      if (s[i][j] == 'S') R = i, C = j;
  bfs();
  int Ans = INF;
  for (int i = 0; i < n; ++i)
    for (int j = 0; j < m; ++j) {
      Ans = min(Ans, F(max(1, dist[i][j])) +
                         F(min(min(i, m - 1 - i), min(j, n - 1 - j))));
    }
  cout << Ans << '\n';
  return 0;
}
