#include <cstdio>
#include <cstring>
#include <algorithm>
#define repu(i,x,y) for (int i=x; i<=y; ++i)
using namespace std;

const int fx[4]={0,0,1,-1},fy[4]={1,-1,0,0};
int n,m,k,d[810][810],q[640100][2],head,tail,ans;
char a[810][810];

void bfs(int x,int y)
{
    memset(d,255,sizeof(d)),d[x][y]=0;
    q[0][0]=x,q[0][1]=y;
    for (; head<=tail; ++head)
    {
        x=q[head][0],y=q[head][1];
        if (d[x][y]<=k)
            ans=min(ans,(min(min(x-1,y-1),min(n-x,m-y))+k-1)/k+1);
        repu(i,0,3)
            if (x+fx[i] && x+fx[i]<=n && y+fy[i] && y+fy[i]<=m
            && a[x+fx[i]][y+fy[i]]!='#' && d[x+fx[i]][y+fy[i]]==-1)
            {
                d[x+fx[i]][y+fy[i]]=d[x][y]+1;
                q[++tail][0]=x+fx[i],q[tail][1]=y+fy[i];
            }
    }
}

int main()
{
    scanf("%d%d%d",&n,&m,&k);
    repu(i,1,n)
        scanf("%s",a[i]+1);
    repu(i,1,n)
        repu(j,1,m)
            if (a[i][j]=='S')
                ans=1<<30,bfs(i,j);
    printf("%d\n",ans);
    return 0;
}