#include <bits/stdc++.h>
using namespace std;
int H, W, K;
int sx, sy;
int dx[4] = {-1, 1, 0, 0}, dy[4] = {0, 0, -1, 1};
char A[810][810];
int B[810][810] = {{0}}, visited[810][810] = {0};
bool in(int x, int y) { return 0 <= x && x <= H - 1 && 0 <= y && y <= W - 1; }
void bfs(void) {
  visited[sx][sy] = 1;
  B[sx][sy] = 1;
  queue<pair<int, int>> Q;
  Q.push({sx, sy});
  while (!Q.empty()) {
    pair<int, int> p = Q.front();
    Q.pop();
    int x = p.first, y = p.second;
    for (int i = 0; i < 4; i++) {
      int nx = x + dx[i], ny = y + dy[i];
      if (in(nx, ny) && visited[nx][ny] == 0 && B[x][y] < K &&
          A[nx][ny] == '.') {
        B[nx][ny] = B[x][y] + 1;
        Q.push({nx, ny});
        visited[nx][ny] = 1;
      }
    }
  }
}
int main() {
  cin >> H >> W >> K;
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      cin >> A[i][j];
      if (A[i][j] == 'S') {
        sx = i;
        sy = j;
      }
    }
  }
  bfs();
  int ans = 1e9;
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      if (B[i][j] != 0) {
        int t = min(min(i, H - 1 - i), min(j, W - j - 1));
        ans = min(ans, 1 + (t + K - 1) / K);
        if (i == 0 || i == H - 1 || j == 0 || j == W - 1) ans = 1;
      }
    }
  }
  cout << ans << endl;
}
