#include <bits/stdc++.h>
#define pb push_back
#define mp make_pair
#define fst first
#define snd second
#define fore(i,a,b) for(int i=a,ThxDem=b;i<ThxDem;++i)
using namespace std;
typedef long long ll;

char b[1024][1024];
int d[1024][1024];
int n,m,k;

bool valid(int i, int j){
	return i>=0&&i<n&&j>=0&&j<m&&b[i][j]!='#';
}

int asd(int i, int j){
	int r=i;
	r=min(r,j);
	r=min(r,n-1-i);
	r=min(r,m-1-j);
	return r;
}

queue<pair<int,int> > q;

int main(){
	scanf("%d%d%d",&n,&m,&k);
	int xs=-1,ys=-1;
	fore(i,0,n){
		scanf("%s",b[i]);
		fore(j,0,m)if(b[i][j]=='S')xs=i,ys=j;
	}
	memset(d,-1,sizeof(d));
	d[xs][ys]=0;
	q.push(mp(xs,ys));
	while(!q.empty()){
		int x=q.front().fst,y=q.front().snd;q.pop();
		fore(i,-1,2)fore(j,-1,2)if(abs(i)+abs(j)==1){
			int xx=x+i,yy=y+j;
			if(valid(xx,yy)&&d[xx][yy]<0){
				d[xx][yy]=d[x][y]+1;
				q.push(mp(xx,yy));
			}
		}
	}
	int r=1<<20;
	fore(i,0,n)fore(j,0,m)if(d[i][j]>=0&&d[i][j]<=k){
		r=min(r,1+(asd(i,j)+k-1)/k);
	}
	printf("%d\n",r);
	return 0;
}