#include<queue>
#include<cctype>
#include<cstdio>
using namespace std;
const int maxn=800,dir[4][2]={0,1,1,0,0,-1,-1,0};
bool a[maxn+10][maxn+10]; int stx,sty,n,m,k,ans=1e9;
struct node{int x,y,d;}; queue<node> q;
void work(int x){ans=min(ans,(x-1)/k+2);}
int main(){
	scanf("%d%d%d",&n,&m,&k);
	for(int i=1;i<=n;++i)
		for(int j=1;j<=m;++j){
			char c=getchar(); for(;!isgraph(c);c=getchar()); 
			if(c=='S') q.push((node){i,j,k}),a[i][j]=1;
			else if(c=='#') a[i][j]=1;
		}
	for(;!q.empty();q.pop()){
		node x=q.front(); 
		if(x.x==1||x.x==n||x.y==1||x.y==m) ans=1;
		else{
			work(x.x-1); work(n-x.x); work(x.y-1); work(m-x.y);
		}
		if(x.d) for(int i=0;i<4;++i){
			node e=(node){x.x+dir[i][0],x.y+dir[i][1],x.d-1};
			if(e.x<=0||e.x>n||e.y<=0||e.y>m||a[e.x][e.y]) continue;
			a[e.x][e.y]=1; q.push(e);
		}
	}
	printf("%d",ans); 
}