// tzl ak IOI! 

#include<bits/stdc++.h>

#define HEAP priority_queue
#define rep(i, n) for(int i = 0, _end_ = (n); i < _end_; ++i)
#define per(i, n) for(int i = (n) - 1; i >= 0 ; --i)
#define forn(i, l, r) for(int i = (l), _end_ = (r); i <= _end_; ++i)
#define nrof(i, r, l) for(int i = (r), _end_ = (l); i >= _end_; --i)
#define FOR(a, b) for(auto (a): (b))
#define mp make_pair
#define mt make_tuple
#define pb push_back
#define X first
#define Y second
#define eps 1e-6
#define pi 3.1415926535897932384626433832795
#define SZ(x) (int)x.size()
#define ALL(x) x.begin(), x.end()
#define FILL(a, b) memset((a), (b), sizeof((a)))
#define MCPY(a, b) memcpy((a), (b), sizeof((b)))

using namespace std;

typedef long long LL;
typedef double flt;
typedef vector<int> vi;
typedef vector<LL> vl;
typedef pair<int,int> pii;
typedef pair<int,LL> pil;
typedef pair<LL,int> pli;
typedef pair<LL,LL> pll;
typedef vector<pil> vil;
typedef vector<pii> vii;
typedef vector<pli> vli;
typedef vector<pll> vll;

const int iinf = 1e9 + 7;
const LL linf = 1ll << 60;
const flt 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; }

#ifdef ONLINE_JUDGE
#define debug(x,c) ;
#else
#define DEBUG
#define debug(x,c) cerr<<#x<<"="<<x<<c;
#endif

void TZL();

void RANK1();

#define tzl int
#define ak main
#define IOI ()
tzl ak IOI
{
#undef tzl
#undef ak
#undef IOI

	TZL();
	RANK1();

#define tzl return
#define caisi 0
#define myy ;
	tzl caisi myy
#undef tzl
#undef caisi
#undef myy
}

//---------------------------head----------------------------

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];
pii 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);
	forn(i, 1, n) scanf("%s", cmap[i] + 1);
	
	FILL(dst, -1);
	int fnt, rar; fnt = rar = 0;
	forn(i, 1, n) forn(j, 1, m) if(cmap[i][j] == 'S')
	{
		q[rar++] = mp(i, j);
		dst[i][j] = 0;
	}

	while(fnt != rar)
	{
		int x = q[fnt].X, y = q[fnt].Y; ++fnt;
		
		rep(k, 4)
		{
			int i = x + dx[k], j = y + dy[k];
			if(check(i, j) && dst[i][j] < 0) dst[i][j] = dst[x][y] + 1, q[rar++] = mp(i, j);
		}
	}

	int ans = iinf;
	forn(i, 1, n) forn(j, 1, m) 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()
{
}

Measured memory_bytes: 9984