#include <bits/stdc++.h>
using namespace std;
#define all(x) (x).begin(),(x).end()
using ll = long long;
using ld = long double;
#define vpl vector<pair<long long,long long>>
#define vl vector<long long>
#define vvl vector<vector<long long>>
#define rep(i, n) for (ll i = 0; i < (ll)(n); i++)
#define rep2(i, s, n) for (ll i = (s); i < (ll)(n); i++)
using pll = pair<long long,long long>;
#define cY cout<<"Yes"<<endl
#define cN cout<<"No"<<endl
const long long INF = 1LL << 60;
long long MOD = 1000000007;
const long double pi = 3.1415926535897932;
#define pb push_back
#define mp make_pair
#define mt make_tuple
using Grid = vector<vector<char>>;
#define vc vector<char>
//(mod m)でのaの逆元を計算する
//a/b(mod m)=a(mod m)*modinv(b,m)
long long modinv(long long a, long long m) {
    long long b = m, u = 1, v = 0;
    while (b) {
        long long t = a / b;
        a -= t * b; swap(a, b);
        u -= t * v; swap(u, v);
    }
    u %= m;
    if (u < 0) u += m;
    return u;
}

//最大最小の入れ替え
template<class T> inline bool chmin(T& a, T b) {
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}
template<class T> inline bool chmax(T& a, T b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}

//約数列挙
vector<long long> divisor(long long n) {
    vector<long long> ret;
    for (long long i = 1; i * i <= n; i++) {
        if (n % i == 0) {
            ret.push_back(i);
            if (i * i != n) ret.push_back(n / i);
        }
    }
    sort(ret.begin(), ret.end()); // 昇順に並べる
    return ret;
}
//コンビネーション
ll nCr(ll n, ll r) {
    ll ans = 1;
    for (ll i = n; i > n - r; --i) {
        ans = ans*i;
    }
    for (ll i = 1 ; i < r + 1; ++i) {
        ans = ans / i;
    }
    return ans;
}
//素因数分解
map< ll, ll > prime_factor(ll n) {
  map< ll, ll > ret;
  for(ll i = 2; i * i <= n; i++) {
    while(n % i == 0) {
      ret[i]++;
      n /= i;
    }
  }
  if(n != 1) ret[n] = 1;
  return ret;
}

//切り上げの割り算は(a + b - 1) / bでできる

//ここから
int main(){
    ll H,W,K;
    cin>>H>>W>>K;
    Grid G(W,vc(H));
    ll sx,sy;
    rep(i,H){
        rep(j,W){
            cin>>G[j][i];
            if(G[j][i]=='S'){
                sx=j;
                sy=i;
            }
        }
    }
    ll dist=INF;
  vector<vector<bool>> visit(W,vector<bool>(H,false));
    queue<pll> q;
    pll w=mp(sx,sy);
    q.push(w);
    map<pll,ll> D;
    D[w]=0;
    ll dx[4]={1,0,-1,0};
    ll dy[4]={0,1,0,-1};
    visit[sx][sy]=true;
    while (!q.empty())
    {
        pll P=q.front();
        q.pop();
        ll x=P.first;
        ll y=P.second;
        dist=min({dist,x,W-x-1,y,H-y-1});
        visit[x][y]=true;
        if(D[P]==K) continue;
        rep(i,4){
            ll nx=x+dx[i];
            ll ny=y+dy[i];
            if(nx<0||ny<0||ny>H-1||nx>W-1||visit[nx][ny])continue;
            if(G[nx][ny]=='.'){
            if(nx==0||nx==W-1||ny==H-1||ny==0){
                cout<<1<<endl;
                return 0;
            }else{
                pll p=mp(nx,ny);
                q.push(p);
                D[p]=D[P]+1;
              visit[nx][ny]=true;
            }
            }
        }
    }
    cout<<1+(dist+K-1)/K<<endl;
}


Measured memory_bytes: 4480