#include<bits/stdc++.h>
using namespace std;
#define N 1116

int n,m,k,d[N][N];
char a[N][N];
queue<pair<int,int> > q;
int dx[]={-1,0,0,1},dy[]={0,-1,1,0};

int read(){
	int x=0,f=1;char ch=getchar();
	for (;!isdigit(ch);ch=getchar()) if (ch=='-') f=-f;
	for (;isdigit(ch);ch=getchar()) x=x*10+ch-'0';
	return x*f;
}

int main(){
	n=read();m=read();k=read();
	memset(d,0x3f,sizeof(d));
	for (int i=1;i<=n;i++){
		scanf(" %s",a[i]+1);
		for (int j=1;j<=m;j++)
			if (a[i][j]=='S')
			d[i][j]=0,q.push(make_pair(i,j));
	}
	while (!q.empty()){
		int x=q.front().first,y=q.front().second;q.pop();
		for (int i=0;i<4;i++){
			int tx=x+dx[i],ty=y+dy[i];
			if (a[tx][ty]=='.'&&d[tx][ty]==0x3f3f3f3f)
			d[tx][ty]=d[x][y]+1,q.push(make_pair(tx,ty));
		}
	}
	int ans=0x3fffffff;
	for (int i=1;i<=n;i++)
		for (int j=1;j<=m;j++)
			if (d[i][j]<=k)
			ans=min(ans,1+(min(min(i-1,n-i),min(j-1,m-j))+k-1)/k);
	printf("%d\n",ans);
	return 0;
}