#include <bits/stdc++.h>
const int dx[4] = {-1, 1, 0, 0}, dy[4] = {0, 0, 1, -1};
const int N = 805;
int n, m, K, dis[N][N];
char mp[N][N];
using namespace std;
struct node {
  int x, y;
};
queue<node> Q;
int main() {
  scanf("%d %d %d", &n, &m, &K);
  int i, j;
  for (i = 1; i <= n; i++) scanf("\n%s", mp[i] + 1);
  for (i = 1; i <= n; i++) {
    for (j = 1; j <= m; j++)
      if (mp[i][j] == 'S') break;
    if (j <= m) break;
  }
  int s = i, t = j, nx, ny;
  memset(dis, -1, sizeof(dis));
  Q.push((node){i, j});
  dis[i][j] = 0;
  while (!Q.empty()) {
    node now = Q.front();
    Q.pop();
    for (i = 0; i < 4; i++) {
      nx = now.x + dx[i], ny = now.y + dy[i];
      if (nx < 1 || ny < 1 || nx > n || ny > m) continue;
      if (mp[nx][ny] == '#') continue;
      if (dis[nx][ny] == -1) {
        dis[nx][ny] = dis[now.x][now.y] + 1;
        Q.push((node){nx, ny});
      }
    }
  }
  int ans = n * m;
  for (i = 1; i <= n; i++)
    for (j = 1; j <= m; j++)
      if (mp[i][j] != '#' && dis[i][j] <= K) {
        if (i == 1 || i == n || j == 1 || j == m)
          ans = 1;
        else
          ans = min(
              ans, (min(min(i - 1, n - i), min(j - 1, m - j)) - 1) / K + 1 + 1);
      }
  cout << ans;
  return 0;
}
