#include <iostream>
#include <queue>
using namespace std;

int H,W,K;
int sx,sy;
int dx[4] = {-1,1,0,0},dy[4] = {0,0,-1,1};
char A[810][810];
int B[810][810] = {{0}},visited[810][810] = {0};
bool in(int x, int y){
	return 0<=x && x<=H-1 && 0<=y && y<=W-1;
}

void bfs(void){
	visited[sx][sy] = 1;
	B[sx][sy] = 0;
	queue<pair<int,int>> Q;
	Q.push({sx,sy});
	while(!Q.empty()){
		pair<int,int> p = Q.front();
		Q.pop();
		int x = p.first,y = p.second;
		for(int i=0;i<4;i++){
			int nx = x+dx[i],ny = y+dy[i];
			if(in(nx,ny) && visited[nx][ny]==0 && B[x][y]<K && A[nx][ny]=='.'){
				B[nx][ny] = B[x][y]+1;
				Q.push({nx,ny});
				visited[nx][ny] = 1;
			}
		}
	}
}

int main(){
	cin >> H >> W >> K;
	for(int i=0;i<H;i++){
		for(int j=0;j<W;j++){
			cin >> A[i][j];
			if(A[i][j]=='S'){
				sx = i; sy = j;
			}
		}
	}
	bfs();
	B[sx][sy] = 1;
	int ans = 1e9;
	for(int i=0;i<H;i++){
		for(int j=0;j<W;j++){
			if(B[i][j]!=0){
				int t = min(min(i,H-1-i),min(j,W-j-1));
				ans = min(ans,1+(t+K-1)/K);
				if(i==0 || i==H-1 || j==0 || j==W-1) ans = 1;
			}
		}
	}
	cout << ans << endl;
}