//header
#ifdef LOCAL
    #include "cxx-prettyprint-master/prettyprint.hpp"
    #define print(x) cout << x << endl
#else
    #define print(...) 42
#endif
    #pragma GCC optimize("Ofast")
    #include <bits/stdc++.h>
    //types
    using namespace std;
    using ll = long long;
    typedef pair < ll , ll >P;
    typedef vector<ll> vl;
    template< typename T >
    using mat = vector< vector< T > >;
    template <std::uint_fast64_t Modulus> class modint {
        using u64 = std::uint_fast64_t;

        public:
        u64 a;

        constexpr modint(const u64 x = 0) noexcept : a(x % Modulus) {}
        constexpr u64 &value() noexcept { return a; }
        constexpr const u64 &value() const noexcept { return a; }
        constexpr modint operator+(const modint rhs) const noexcept {
            return modint(*this) += rhs;
        }
        constexpr modint operator-(const modint rhs) const noexcept {
            return modint(*this) -= rhs;
        }
        constexpr modint operator*(const modint rhs) const noexcept {
            return modint(*this) *= rhs;
        }
        constexpr modint operator/(const modint rhs) const noexcept {
            return modint(*this) /= rhs;
        }
        constexpr modint &operator+=(const modint rhs) noexcept {
            a += rhs.a;
            if (a >= Modulus) {
            a -= Modulus;
            }
            return *this;
        }
        constexpr modint &operator-=(const modint rhs) noexcept {
            if (a < rhs.a) {
            a += Modulus;
            }
            a -= rhs.a;
            return *this;
        }
        constexpr modint &operator*=(const modint rhs) noexcept {
            a = a * rhs.a % Modulus;
            return *this;
        }
        constexpr modint &operator/=(modint rhs) noexcept {
            u64 exp = Modulus - 2;
            while (exp) {
            if (exp % 2) {
                *this *= rhs;
            }
            rhs *= rhs;
            exp /= 2;
            }
            return *this;
        }
        };
    //abbreviations
    #define all(x) (x).begin(), (x).end()
    #define reverse(x) (x).rbegin(), (x).rend()
    #define rep2(i,a,b) for(ll i=(a);i<(b);++i)
    #define rep(i,n) for(ll i=0;i<(n);++i)
    #define SZ(x) ((ll)(x).size())
    #define sum(x) accumulate(begin(x), end(x), 0LL)//?
    #define pb(x) push_back(x)
    //functions
    ll gcd(ll a, ll b) { return b ? gcd(b, a%b) : a; }
    template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
    template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }
    template< typename T >
    T mod_pow(T x, T n, const T &p) {
        T ret = 1;
        while(n > 0) {
            if(n & 1) (ret *= x) %= p;
            (x *= x) %= p;
            n >>= 1;
        }
        return ret;
    }
    uint64_t my_rand(void) {
        static uint64_t x = 88172645463325252ULL;
        x = x ^ (x << 13); x = x ^ (x >> 7);
        return x = x ^ (x << 17);
    }

//constant
#define INF 1'010'000'000'000'000'017LL
#define mod 1000000007LL
#define eps 0.0001
//library

//main
int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout<<fixed<<setprecision(20);
    ll H, W, K; cin >> H >> W >> K;
    mat<char> A(H, vector<char>(W));
    ll sx, sy;
    rep(i, H)rep(j, W){
        cin >> A[i][j];
        if(A[i][j] == 'S'){
            sx = i;
            sy = j;
        }
    }
    vl dx = {0, 1, 0, -1};
    vl dy = {1, 0, -1, 0};
    mat<ll> dist(H, vl(W, -1));
    ll D = min({sx, sy, H-sx-1, W-sy-1});
    deque<P> que;
    que.push_back(P(sx, sy));
    dist[sx][sy] = 0;
    while(que.size()){
        P p = que.front();que.pop_front();
        ll d = dist[p.first][p.second];
        if(d==K)break;
        rep(i, 4){
            ll nx = p.first+dx[i], ny = p.second+dy[i];
            if(0<=nx&&nx<H&&0<=ny&&ny<W&&A[nx][ny] != '#'&&dist[nx][ny] == -1){
                dist[nx][ny] = d+1;
                chmin(D, min({nx, ny, H-nx-1, W-ny-1}));
                que.push_back(P(nx, ny));
            }
        }
    }
    if(D == 0)cout << 1 << endl;
    else cout << (D-1)/K+2 << endl;
}

Measured memory_bytes: 6016