#include<bits/stdc++.h>
#define L long long
#define vi vector<int>
#define pb push_back
#define pi pair<int,int>
#define pii pair<pi,int>
#define aa first
#define bb second
#define xx aa.aa
#define yy aa.bb
#define zz bb
#define mp make_pair
#define mpp(a,b,c) mp(mp(a,b),c)
using namespace std;
int n,m,t,f[810][810],dx[4]={1,-1,0,0},dy[4]={0,0,1,-1},x[1000000],y[1000000],r,p=1e9;
char s[810][810];
inline void chk(int i,int j)
{
	int k=min(min(i-1,j-1),min(n-i,m-j));
	k=(k?((k-1)/t+1):0);
	p=min(p,k+1);
}
int main()
{
	//freopen(".in","r",stdin);
	//freopen(".out","w",stdout);
	int i,j;
	scanf("%d%d%d",&n,&m,&t);
	for(i=1;i<=n;i++)
	  scanf("%s",&s[i][0]+1);
	for(i=1;i<=n;i++)
	  for(j=1;j<=m;j++)
	    if(s[i][j]=='S')
	      {
		   r=1;
		   x[1]=i;
		   y[1]=j;
		   f[i][j]=1;
		  }
	for(i=1;i<=r && f[x[i]][y[i]]<=t;i++)
	  for(j=0;j<4;j++)
	    if(x[i]+dx[j]>0 && x[i]+dx[j]<=n && y[i]+dy[j]>0 && y[i]+dy[j]<=m && !f[x[i]+dx[j]][y[i]+dy[j]] && s[x[i]+dx[j]][y[i]+dy[j]]=='.')
	      {
		   f[x[i]+dx[j]][y[i]+dy[j]]=f[x[i]][y[i]]+1;
		   x[++r]=x[i]+dx[j];
		   y[r]=y[i]+dy[j];
		  }
	for(i=1;i<=r;i++)
	  chk(x[i],y[i]);
	printf("%d\n",p);
	return 0;
}
