#include <iostream>
#include <queue>
#include <algorithm>
using namespace std;

bool inside(int x, int y, int xlim, int ylim){
	return 0 <= x && x < xlim && 0 <= y && y < ylim;
}

struct puni{
	int x, y, d;
	puni(int x, int y, int d){
		this->x = x;
		this->y = y;
		this->d = d;
	}
};

int main(){
	constexpr int dd[] = {0, 1, 0, -1, 0};
	int h, w, k;
	cin >> h >> w >> k;
	string s[h];
	for(int i = 0; i < h; i++) cin >> s[i];
	queue<puni> q;
	for(int i = 0; i < h; i++) for(int j = 0; j < w; j++) if(s[i][j] == 'S'){
		s[i][j] = '.';
		q.push(puni(i, j, 0));
	}
	int ans = 1e9, muni[h][w];
	fill(muni[0], muni[h], 1e9);
	while(!q.empty()){
		puni p = q.front();
		q.pop();
		if(muni[p.x][p.y] <= p.d || k < p.d) continue;
		muni[p.x][p.y] = p.d;
		int d = min({p.x, p.y, h - p.x - 1, w - p.y - 1});
		ans = min(ans, (d + k - 1) / k);
		for(int i = 0; i < 4; i++){
			int nx = p.x + dd[i], ny = p.y + dd[i + 1];
			if(inside(nx, ny, h, w) && s[nx][ny] == '.'){
				q.push(puni(nx, ny, p.d + 1));
			}
		}
	}
	cout << ans + 1 << endl;
}