#include<cstdio>
#include<cstring>
#include<cmath>
#include<algorithm>
using namespace std;
int h,w,K,ans=1<<30,i,j,k,qx[805*805],qy[805*805],bg,ed,f[10][5]={{-1,0},{1,0},{0,-1},{0,1}},dis[805][805];
char s[805][805];
bool v[805][805];
int main()
{
	scanf("%d%d%d",&h,&w,&K);
	for(i=1;i<=h;++i)
	{
		scanf("%s",s[i]+1);
		for(j=1;j<=w;++j)
			dis[i][j]=1000000;
	}
	for(i=1;i<=h;++i)
	{
		for(j=1;j<=w;++j)
			if(s[i][j]=='S')
				break;
		if(j<=w)
			break;
	}
	bg=ed=1;
	qx[1]=i,qy[1]=j;
	v[i][j]=true;
	dis[i][j]=0;
	while(bg<=ed)
	{
		for(i=0;i<4;++i)
		{
			j=qx[bg]+f[i][0],k=qy[bg]+f[i][1];
			if(j>=1&&j<=h&&k>=1&&k<=w&&s[j][k]!='#'&&!v[j][k])
			{
				v[j][k]=true;
				++ed;
				qx[ed]=j,qy[ed]=k;
				dis[j][k]=dis[qx[bg]][qy[bg]]+1;
			}
		}
		++bg;
	}
	for(i=1;i<=h;++i)
		for(j=1;j<=w;++j)
			if(s[i][j]!='#'&&dis[i][j]<=K)
			{
				int g=min(min(i-1,j-1),min(h-i,w-j));
				if(g==0)
					ans=1;
				else
					ans=min(ans,(g-1)/K+2);
			}
	printf("%d",ans);
	return 0;
}
