#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef double D;
typedef pair<int,int> P;
#define M 1000000007
#define F first
#define S second
#define PB push_back
#define INF 1000000000
int h,w,k,d[1005][1005],sx,sy,dx[4]={0,1,0,-1},dy[4]={1,0,-1,0},ans=INF;
int main(void){
    scanf("%d%d%d",&h,&w,&k);
    for(int i=0;i<h;i++){
		for(int j=0;j<w;j++){
			char c;
			scanf(" %c",&c);
			if(c=='S')sx=j,sy=i;
			if(c=='#')d[i][j]=INF;
			else d[i][j]=-1;
		}
	}
	queue<P>bfs;
	d[sy][sx]=0;
	bfs.push(P(sy,sx));
	while(!bfs.empty()){
		int x=bfs.front().S,y=bfs.front().F;
		bfs.pop();
		for(int i=0;i<4;i++){
			int nx=x+dx[i],ny=y+dy[i];
			if(nx>=0&&nx<w&&ny>=0&&ny<h&&d[ny][nx]==-1){
				d[ny][nx]=d[y][x]+1;
				bfs.push(P(ny,nx));
			}
		}
	}
	for(int i=0;i<h;i++){
		for(int j=0;j<w;j++){
			if(d[i][j]!=-1&&d[i][j]<=k){
				int p=min(min(i,h-i-1),min(j,w-j-1));
				ans=min(ans,(p+k-1)/k+1);
			}
		}
	}
	printf("%d\n",ans);
}
