#include <iostream>
#include <stdio.h>
#include <string.h>
#include <queue>
#include <algorithm>
using namespace std;
const int inf=0x3f3f3f3f;
const int rd[4]={1,0,-1,0};
const int cd[4]={0,1,0,-1};

int h,w,k,sr,sc,d[805][805],res=inf;
char a[805][805];

inline bool inside(int r,int c){
    return r>=0 && r<h && c>=0 && c<w;
}

inline int casts(int r,int c){
    int x0=c,x1=w-c-1,y0=r,y1=h-r-1;
    return (min(min(x0,x1),min(y0,y1))+k-1)/k;
}

int main(){
    memset(d,inf,sizeof d);
    scanf("%d %d %d",&h,&w,&k);
    for(int i=0;i<h;i++){
        scanf("%s",a[i]);
        for(int j=0;j<w;j++)if(a[i][j]=='S')sr=i,sc=j;
    }
    queue<pair<int,int> > q;
    q.push(make_pair(sr,sc));
    d[sr][sc]=0;
    while(!q.empty()){
        pair<int,int> p=q.front();q.pop();
        res=min(res,casts(p.first,p.second)+1);
        if(d[p.first][p.second]==k)continue;
        for(int k=0;k<4;k++){
            int rr=p.first+rd[k],cc=p.second+cd[k];
            if(!inside(rr,cc) || a[rr][cc]=='#')continue;
            if(d[rr][cc]!=inf)continue;
            q.push(make_pair(rr,cc));
            d[rr][cc]=d[p.first][p.second]+1;
        }
    }
    printf("%d\n",res);
    return 0;
}
