#include <stdio.h>
#include <queue>
using namespace std;

int H,W,K; char map[808][808]; int dist[808][808];

int main()
{
	scanf ("%d %d %d",&H,&W,&K);
	queue<pair<int, int> > Q;
	for (int i=0;i<H;i++){
		scanf ("%s",map[i]);
		for (int j=0;j<W;j++){
			dist[i][j] = -1;
			if (map[i][j] == 'S'){
				Q.push({i,j}); dist[i][j] = 0;
			}
		}
	}

	while (!Q.empty()){
		int x = Q.front().first, y = Q.front().second; Q.pop();
		int dx[4] = {0,1,0,-1};
		int dy[4] = {1,0,-1,0};
		for (int k=0;k<4;k++){
			int px = x + dx[k], py = y + dy[k];
			if (px < 0 || px >= H || py < 0 || py >= W) continue;
			if (dist[px][py] == -1 && map[px][py] != '#'){
				Q.push({px,py}); dist[px][py] = dist[x][y] + 1;
			}
		}
	}

	int ans = 0x7fffffff;
	for (int i=0;i<H;i++) for (int j=0;j<W;j++) if (dist[i][j] != -1 && dist[i][j] <= K){
		int r = (min(min(i,H-i-1),min(j,W-j-1)) + K - 1) / K + 1;
		ans = min(r,ans);
	}
	printf ("%d\n",ans);

	return 0;
}