#include<bits/stdc++.h>
using namespace std;
char c[880][880];
int n,m,k,x,y,dis[880][880],mm=1e9;
int dx[]={1,-1,0,0},dy[]={0,0,1,-1};
int main()
{
	cin>>n>>m>>k;
	for(int i=0;i<n;i++)
	{
		cin>>c[i];
		for(int j=0;j<m;j++)
			if(c[i][j]=='S')
			{
				x=i;
				y=j;
			}
	}
	queue<pair<int,int> >que;
	que.push(make_pair(x,y));
	memset(dis,-1,sizeof(dis));
	dis[x][y]=0;
	while(!que.empty())
	{
		int a=que.front().first;
		int b=que.front().second;
		que.pop();
		if(dis[a][b]>k)
			break;
		if(a==0||b==0||a==n-1||b==m-1)
		{
			cout<<1<<endl;
			return 0;
		}
		mm=min(mm,min(min(a,n-a-1),min(b,m-b-1)));
		for(int i=0;i<4;i++)
		{
			int u=a+dx[i],v=b+dy[i];
			if(c[u][v]!='#'&&dis[u][v]==-1)
			{
				dis[u][v]=dis[a][b]+1;
				que.push(make_pair(u,v));
			}
		}
	}
	cout<<(mm+k-1)/k+1<<endl;
	return 0;
}