#include <bits/stdc++.h>
using namespace std;

#ifdef SG
	#include <debug.h>
#else
	template<typename T> struct outputer;
	struct outputable {};
	#define PRINT(...)
	#define OUTPUT(...)
	#define show(...)
	#define debug(...)
	#define deepen(...)
	#define timer(...)
	#define fbegin(...)
	#define fend
	#define pbegin(...)
	#define pend
#endif

#define ARG4(_1,_2,_3,_4,...) _4

#define forn3(i,l,r) for (int i = int(l); i < int(r); ++i)
#define forn2(i,n) forn3 (i, 0, n)
#define forn(...) ARG4(__VA_ARGS__, forn3, forn2) (__VA_ARGS__)

#define ford3(i,l,r) for (int i = int(r) - 1; i >= int(l); --i)
#define ford2(i,n) ford3 (i, 0, n)
#define ford(...) ARG4(__VA_ARGS__, ford3, ford2) (__VA_ARGS__)

#define ve vector
#define pa pair
#define tu tuple
#define mp make_pair
#define mt make_tuple
#define pb emplace_back
#define fs first
#define sc second
#define all(a) (a).begin(), (a).end()
#define sz(a) ((int)(a).size())

typedef long double ld;
typedef int64_t ll;
typedef uint64_t ull;
typedef uint32_t ui;
typedef uint16_t us;
typedef uint8_t uc;
typedef pa<int, int> pii;
typedef pa<int, ll> pil;
typedef pa<ll, int> pli;
typedef pa<ll, ll> pll;
typedef ve<int> vi;

template<typename T> inline auto sqr (T x) -> decltype(x * x) {return x * x;}
template<typename T1, typename T2> inline bool umx (T1& a, T2 b) {if (a < b) {a = b; return 1;} return 0;}
template<typename T1, typename T2> inline bool umn (T1& a, T2 b) {if (b < a) {a = b; return 1;} return 0;}

const int N = 800;
const int M = 800;

struct Input {
	int n, m, k;
	string a[N];
	
	bool read () {
		if (!(cin >> n >> m >> k)) {
			return 0;
		}
		getline(cin, a[0]);
		forn (i, n) {
			getline(cin, a[i]);
		}
		return 1;
	}

	void init (const Input &input) {
		*this = input;
	}
};

struct Data: Input {
	int ans;
	
	void write () {
		cout << ans << endl;
	}
};


namespace Main {
	const int inf = 1000000000;
	
	const int dx[4] = {-1, 0, 1, 0};
	const int dy[4] = {0, -1, 0, 1};
	
	struct Solution: Data {
		int num[N][M];
		int d[N][N];
		
		void solve () {
			ve<pii> q;
			forn (i, n) {
				forn (j, m) {
					num[i][j] = min(min(i, n - 1 - i), min(j, m - 1 - j));
					d[i][j] = inf;
					if (a[i][j] == 'S') {
						d[i][j] = 0;
						q.pb(mp(i, j));
					}
				}
			}
			
			ans = inf;
			
			forn (i, sz(q)) {
				if (d[q[i].fs][q[i].sc] == 0 && num[q[i].fs][q[i].sc] == 0) {
					umn(ans, 0);
				} else {
					umn(ans, (max(d[q[i].fs][q[i].sc], k) + num[q[i].fs][q[i].sc] + k - 1) / k);
				}
				forn (j, 4) {
					int x1 = q[i].fs + dx[j];
					int y1 = q[i].sc + dy[j];
					if (x1 >= 0 && x1 < n && y1 >= 0 && y1 < m && a[x1][y1] != '#' && umn(d[x1][y1], d[q[i].fs][q[i].sc] + 1)) {
						q.pb(mp(x1, y1));
					}
				}
			}
		}
		
		void clear () {
			*this = Solution();
		}
	};
}


Main::Solution sol;

int main () {
	cout.setf(ios::showpoint | ios::fixed);
	cout.precision(20);

	#ifdef SG
		freopen((problemname + ".in").c_str(), "r", stdin);
//		freopen((problemname + ".out").c_str(), "w", stdout);
		while (sol.read()) {
			sol.solve();
			sol.write();
			sol.clear();
		}
	#else
		sol.read();
		sol.solve();
		sol.write();
	#endif
	
	/*
	int t;
	cin >> t;
	forn (i, t) {
		sol.read();
		sol.solve();
		sol.write();
		sol.clear();
	}
	*/
	
	return 0;
}


Measured memory_bytes: 16240