#include <bits/stdc++.h>

#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define REP(i,a) FOR(i,0,a)

using namespace std;
typedef pair<int,int> P;
const int INF=1e8;
int dx[4]={1,0,-1,0},dy[4]={0,1,0,-1};

const int MAX_W=800,MAX_H=800;

int H,W,K;
char A[MAX_H][MAX_W+1];

int dist[MAX_H][MAX_W];

int roundup(int x,int y){
	return (x+y-1)/y;
}

int main(){
	cin>>H>>W>>K;
	REP(i,H){
		cin>>A[i];
	}
	queue<P> que;
	REP(h,H){
		REP(w,W){
			dist[h][w]=INF;
			if (A[h][w]=='S'){
				que.push(P(h,w));
				dist[h][w]=0;
			}
		}
	}
	while(!que.empty()){
		P p=que.front();
		que.pop();
		int h=p.first;
		int w=p.second;
		REP(i,4){
			int h2=h+dy[i],w2=w+dx[i];
			if (0<=h2 && h2<H && 0<=w2 && w2<W && A[h2][w2]!='#' && dist[h][w]+1<dist[h2][w2]){
				dist[h2][w2]=dist[h][w]+1;
				que.push(P(h2,w2));
			}
		}
	}
	int ans=INF;
	REP(h,H){
		REP(w,W){
			if (dist[h][w]<=K){
				ans=min({ans,roundup(h,K),roundup(w,K),roundup(H-1-h,K),roundup(W-1-w,K)});
			}
		}
	}
	cout<<ans+1<<endl;
	return 0;
}