#include<cstdio>
#include<algorithm>
using namespace std;
int Q[1010000][2],head,tail,D[810][810];
int n,m,K,sx,sy;
char p[810][810];
void Ins(int x,int y,int d){
	if(D[x][y]<=d||p[x][y]!='.'){
		return;
	}
	D[x][y]=d;
	tail++;
	Q[tail][0]=x,Q[tail][1]=y;
} 
int main(){
	int i,j,x,y;
	scanf("%d%d%d",&n,&m,&K);
	for(i=1;i<=n;i++){
		scanf("%s",p[i]+1);
		for(j=1;j<=m;j++){
			if(p[i][j]=='S'){
				sx=i,sy=j,p[i][j]='.';
			}
			D[i][j]=1e9;
		}
	}
	Ins(sx,sy,0);
	while(head<tail){
		head++;
		x=Q[head][0],y=Q[head][1];
		Ins(x+1,y,D[x][y]+1);
		Ins(x,y+1,D[x][y]+1);
		Ins(x-1,y,D[x][y]+1);
		Ins(x,y-1,D[x][y]+1);
	}
	int res=1e9;
	for(i=1;i<=n;i++){
		for(j=1;j<=m;j++){
			if(D[i][j]<=K){
				res=min(res,1+(min(min(i-1,n-i),min(j-1,m-j))+K-1)/K);
			}
		}
	}
	printf("%d\n",res);
}