#include<bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0;i<(n);i++)
using P=pair<int,int>;
int inf=1e9;
queue<P> que;
vector<int>dx={0,0,1,-1};
vector<int>dy={1,-1,0,0};

int main(){
	int h,w,k;cin>>h>>w>>k;
	vector<string>a(h);
	for(auto&& u:a)cin>>u;
	vector<vector<int>>d(h,vector<int>(w,inf));
	rep(i,h)rep(j,w)if(a[i][j]=='S'){que.push(make_pair(i,j));d[i][j]=0;}
	while(!que.empty()){
		P z=que.front();que.pop();
		rep(i,4){
			int x,y;x=z.first+dx[i];y=z.second+dy[i];
			if(x<0||x>=h||y<0||y>=w)continue;
			if(d[x][y]==inf&&a[x][y]=='.' ){
				d[x][y]=d[z.first][z.second]+1;
				que.push(make_pair(x,y));
			}			

		}
	}	
	int mn=inf;
	rep(i,h)rep(j,w){if(d[i][j]<=k)mn=min({mn,i,j,h-1-i,w-1-j});}
	if (mn==0)cout<<1<<endl; 
	else  cout<<(mn-1)/k+2<<endl;
}
