#include <bits/stdc++.h>
using namespace std;
const int N = 8e2 + 7;
char t[N][N];
int n, m, k;
int dis[N][N];
deque<pair<int, int> > d;
int main() {
  cin >> n >> m >> k;
  for (int i = 1; i <= n; i++)
    for (int j = 1; j <= m; j++) {
      cin >> t[i][j];
      if (t[i][j] == 'S') {
        dis[i][j] = 1;
        d.push_back({i, j});
      }
    }
  int res = n * m;
  while (d.size()) {
    int x = d.front().first, y = d.front().second;
    d.pop_front();
    if (dis[x][y] - 1 <= k) {
      res = min({res, 1 + (x + k - 1) / k, 1 + (y + k - 1) / k,
                 1 + (n - x + k - 1) / k, 1 + (m - y + k - 1) / k});
    }
    for (int dx = x - 1; dx <= x + 1; dx += 2) {
      if (dx >= 0 && dx <= n && t[dx][y] != '#' && !dis[dx][y])
        dis[dx][y] = dis[x][y] + 1, d.push_back({dx, y});
    }
    for (int dy = y - 1; dy <= y + 1; dy += 2) {
      if (dy >= 0 && dy <= n && t[x][dy] != '#' && !dis[x][dy])
        dis[x][dy] = dis[x][y] + 1, d.push_back({x, dy});
    }
  }
  cout << res;
  return 0;
}
