#include <cstdio>
#include <queue>

using namespace std;

const int maxn=810;

int vis[maxn][maxn],walkx[]={0,0,-1,1},walky[]={1,-1,0,0};
char str[maxn][maxn];

struct node
{
	int x,y,t;
};

queue <node> q;

int main()
{
	int n,m,k;
	scanf("%d%d%d",&n,&m,&k);
	for(int i=1;i<=n;i++)
	{
		scanf("%s",&str[i][1]);
		for(int j=1;j<=m;j++)
		{
			if(str[i][j]=='S')
			{
				q.push((node){i,j,0});
				vis[i][j]=1;
			}
		}
	}
	int ans=2e9;
	while(!q.empty())
	{
		node t=q.front();q.pop();
		int tt=min(t.x,t.y);
		ans=min(ans,(tt-1)/k+((tt-1)%k!=0));
		ans=min(ans,(n-t.x)/k+((n-t.x)%k!=0));
		ans=min(ans,(m-t.y)/k+((m-t.y)%k!=0));
		if(t.t==k)continue;
		for(int i=0;i<4;i++)
		{
			int newx=t.x+walkx[i],newy=t.y+walky[i];
			if(newx>0&&newx<=n&&newy>0&&newy<=m&&!vis[newx][newy]&&str[newx][newy]!='#')
			{
				q.push((node){newx,newy,t.t+1});
				vis[newx][newy]=1;
			}
		}
	}
	ans++;
	printf("%d\n",ans);
	return 0;
} 