#include <bits/stdc++.h>
using namespace std;
const int iinf = 1e9 + 7;
const long long linf = 1ll << 60;
const double dinf = 1e60;
template <typename T>
inline void scf(T &x) {
  bool f = 0;
  x = 0;
  char c = getchar();
  while ((c < '0' || c > '9') && c != '-') c = getchar();
  if (c == '-') {
    f = 1;
    c = getchar();
  }
  while (c >= '0' && c <= '9') {
    x = x * 10 + c - '0';
    c = getchar();
  }
  if (f) x = -x;
  return;
}
template <typename T1, typename T2>
void scf(T1 &x, T2 &y) {
  scf(x);
  return scf(y);
}
template <typename T1, typename T2, typename T3>
void scf(T1 &x, T2 &y, T3 &z) {
  scf(x);
  scf(y);
  return scf(z);
}
template <typename T1, typename T2, typename T3, typename T4>
void scf(T1 &x, T2 &y, T3 &z, T4 &w) {
  scf(x);
  scf(y);
  scf(z);
  return scf(w);
}
inline char mygetchar() {
  char c = getchar();
  while (c == ' ' || c == '\n') c = getchar();
  return c;
}
template <typename T>
void chkmax(T &x, const T &y) {
  if (y > x) x = y;
  return;
}
template <typename T>
void chkmin(T &x, const T &y) {
  if (y < x) x = y;
  return;
}
void TZL();
void RANK1();
int main() {
  TZL();
  RANK1();
  return 0;
}
const int dx[] = {-1, 1, 0, 0};
const int dy[] = {0, 0, -1, 1};
const int N = 880;
int n, m, k;
char cmap[N][N];
int dst[N][N];
pair<int, int> q[N * N];
bool check(int x, int y) {
  return x > 0 && y > 0 && x <= n && y <= m && cmap[x][y] == '.' ||
         cmap[x][y] == 'S';
}
int d(int x, int y) {
  int d1 = x - 1, d2 = y - 1, d3 = n - x, d4 = m - y;
  return min(min(d1, d2), min(d3, d4));
}
void TZL() {
  scf(n, m, k);
  for (int i = (1), _end_ = (n); i <= _end_; ++i) scanf("%s", cmap[i] + 1);
  memset((dst), (-1), sizeof((dst)));
  int fnt, rar;
  fnt = rar = 0;
  for (int i = (1), _end_ = (n); i <= _end_; ++i)
    for (int j = (1), _end_ = (m); j <= _end_; ++j)
      if (cmap[i][j] == 'S') {
        q[rar++] = make_pair(i, j);
        dst[i][j] = 0;
      }
  while (fnt != rar) {
    int x = q[fnt].first, y = q[fnt].second;
    ++fnt;
    for (int k = 0, _end_ = (4); k < _end_; ++k) {
      int i = x + dx[k], j = y + dy[k];
      if (check(i, j) && dst[i][j] < 0) dst[i][j] = dst[x][y] + 1;
    }
  }
  int ans = iinf;
  for (int i = (1), _end_ = (n); i <= _end_; ++i)
    for (int j = (1), _end_ = (m); j <= _end_; ++j)
      if (~dst[i][j] && dst[i][j] <= k) chkmin(ans, d(i, j));
  if (ans == 0)
    puts("1");
  else
    printf("%d\n", (ans + k - 1) / k + 1);
  return;
}
void RANK1() {}
