#include <iostream>
#include <vector>
#include <cstdio>
#include <sstream>
#include <map>
#include <string>
#include <algorithm>
#include <queue>
#include <cmath>
#include <functional>
#include <set>
#include <ctime>
#include <random>
#include <chrono>
#include <cassert>
#include <tuple>
#include <utility>
using namespace std;

namespace {
  using Integer = long long; //__int128;
  template<class T, class S> istream& operator >> (istream& is, pair<T,S>& p){return is >> p.first >> p.second;}
  template<class T> istream& operator >> (istream& is, vector<T>& vec){for(T& val: vec) is >> val; return is;}
  template<class T> istream& operator ,  (istream& is, T& val){ return is >> val;}
  template<class T, class S> ostream& operator << (ostream& os, const pair<T,S>& p){return os << p.first << " " << p.second;}
  template<class T> ostream& operator << (ostream& os, const vector<T>& vec){for(size_t i=0; i<vec.size(); i++) os << vec[i] << (i==vec.size()-1?"":" "); return os;}
  template<class T> ostream& operator ,  (ostream& os, const T& val){ return os << " " << val;}

  template<class H> void print(const H& head){ cout << head; }
  template<class H, class ... T> void print(const H& head, const T& ... tail){ cout << head << " "; print(tail...); }
  template<class ... T> void println(const T& ... values){ print(values...); cout << endl; }

  template<class H> void eprint(const H& head){ cerr << head; }
  template<class H, class ... T> void eprint(const H& head, const T& ... tail){ cerr << head << " "; eprint(tail...); }
  template<class ... T> void eprintln(const T& ... values){ eprint(values...); cerr << endl; }

  class range{ Integer start_, end_, step_; public: struct range_iterator{ Integer val, step_; range_iterator(Integer v, Integer step) : val(v), step_(step) {} Integer operator * (){return val;} void operator ++ (){val += step_;} bool operator != (range_iterator& x){return step_ > 0 ? val < x.val : val > x.val;} }; range(Integer len) : start_(0), end_(len), step_(1) {} range(Integer start, Integer end) : start_(start), end_(end), step_(1) {} range(Integer start, Integer end, Integer step) : start_(start), end_(end), step_(step) {} range_iterator begin(){ return range_iterator(start_, step_); } range_iterator   end(){ return range_iterator(  end_, step_); } };

  inline string operator "" _s (const char* str, size_t size){ return move(string(str)); }
  constexpr Integer my_pow(Integer x, Integer k, Integer z=1){return k==0 ? z : k==1 ? z*x : (k&1) ? my_pow(x*x,k>>1,z*x) : my_pow(x*x,k>>1,z);}
  constexpr Integer my_pow_mod(Integer x, Integer k, Integer M, Integer z=1){return k==0 ? z%M : k==1 ? z*x%M : (k&1) ? my_pow_mod(x*x%M,k>>1,M,z*x%M) : my_pow_mod(x*x%M,k>>1,M,z);}
  constexpr unsigned long long operator "" _ten (unsigned long long value){ return my_pow(10,value); }

  inline int k_bit(Integer x, int k){return (x>>k)&1;} //0-indexed

  mt19937 mt(chrono::duration_cast<chrono::nanoseconds>(chrono::steady_clock::now().time_since_epoch()).count());

  template<class T> string join(const vector<T>& v, const string& sep){ stringstream ss; for(size_t i=0; i<v.size(); i++){ if(i>0) ss << sep; ss << v[i]; } return ss.str(); }

  inline string operator * (string s, int k){ string ret; while(k){ if(k&1) ret += s; s += s; k >>= 1; } return ret; }
}
constexpr long long mod = 9_ten + 7;

int dx[] = {0, 0, 1,-1, 1, 1,-1,-1};
int dy[] = {1,-1, 0, 0, 1,-1, 1,-1};

int main(){
  int h,w,k;
  cin >> h,w,k;

  vector<string> a(h);
  cin >> a;

  int start = -1;
  for(int i=0; i<h && start == -1; i++){
    for(int j=0; j<w && start == -1; j++){
      if( a[i][j] == 'S' ){
        start = i*w + j;
        break;
      }
    }
  }

  vector<vector<int>> dp(h, vector<int>(w, 1e8));
  queue< pair<int,int> > q;
  q.push( {start, 0} );
  dp[ start/w ][ start%w ] = 0;
  while(q.size()){
    auto p = q.front(); q.pop();
    int y = p.first / w;
    int x = p.first % w;
    int d = p.second;

    if(y==0 || x==0 || y==h-1 || x==w-1){
      println(1);
      return 0;
    }

    for(int k__=0; k__<4; k__++){
      int new_x = x + dx[k__];
      int new_y = y + dy[k__];
      if(new_x < 0 || new_x >= w || new_y < 0 || new_y >= h) continue;
      
      if( a[new_y][new_x] == '#' ){
        continue;
      }

      int dd = d+1;
      if( dd > k ) continue;
      if( dp[new_y][new_x] > dd ){
        dp[new_y][new_x] = dd;
        q.push( {new_y*w + new_x, dd} );
      }
    }
  }

  for(int i : range(h)) for(int j : range(w)){
    if(dp[i][j] != 1e8){
      dp[i][j] = 0;
      q.push( {i*w+j, 0} );
    }
  }

  while(q.size()){
    auto p = q.front(); q.pop();
    int y = p.first / w;
    int x = p.first % w;
    int d = p.second;

    if(y==0 || x==0 || y==h-1 || x==w-1){
      println( (d+k-1) / k + 1 );
      return 0;
    }

    for(int k__=0; k__<4; k__++){
      int new_x = x + dx[k__];
      int new_y = y + dy[k__];
      if(new_x < 0 || new_x >= w || new_y < 0 || new_y >= h) continue;
      
      int dd = d+1;
      if( dp[new_y][new_x] > dd ){
        dp[new_y][new_x] = dd;
        q.push( {new_y*w + new_x, dd} );
      }
    }
  }

  return 0;
}


Measured memory_bytes: 3968