/* ---------- STL Libraries ---------- */

// IO library
#include <cstdio>
#include <fstream>
#include <iomanip>
#include <ios>
#include <iostream>

// algorithm library
#include <algorithm>
#include <cmath>
#include <numeric>
#include <random>

// container library
#include <array>
#include <bitset>
#include <deque>
#include <map>
#include <queue>
#include <set>
#include <string>
#include <tuple>
#include <vector>

/* ---------- Namespace ---------- */

using namespace std;

/* ---------- Type Abbreviation ---------- */

template <typename T>
using PQ = priority_queue<T>;
template <typename T>
using GPQ = priority_queue<T, vector<T>, greater<T>>;

using ll = long long;

#define fst first
#define snd second
#define mp make_pair
#define mt make_tuple

/* ---------- conversion ---------- */

#define INT(c) static_cast<int>(c)
#define CHAR(n) static_cast<char>(n)
#define LL(n) static_cast<ll>(n)
#define DOUBLE(n) static_cast<double>(n)

/* ---------- container ---------- */

#define ALL(v) (v).begin(), (v).end()
#define SIZE(v) (LL((v).size()))

#define FIND(v, k) (v).find(k) != (v).end()
#define VFIND(v, k) find(ALL(v), k) != (v).end()

#define gsort(b, e) sort(b, e, greater<decltype(*b)>())

/* ----------- debug ---------- */

template <class T>
ostream& operator<<(ostream& os, vector<T> v) {
    os << "[";
    for (auto vv : v)
        os << vv << ",";
    return os << "]";
}

template <class T>
ostream& operator<<(ostream& os, set<T> v) {
    os << "[";
    for (auto vv : v)
        os << vv << ",";
    return os << "]";
}

template <class L, class R>
ostream& operator<<(ostream& os, pair<L, R> p) {
    return os << "(" << p.fst << "," << p.snd << ")";
}

/* ---------- Constants ---------- */

// const ll MOD = 1e9 + 7;
// const int INF = 1 << 25;
// const ll INF = 1LL << 50;
// const double PI = acos(-1);
// const double EPS = 1e-10;
// mt19937 mert(LL(time(0)));

/* ---------- Short Functions ---------- */

template <typename T>
T sq(T a) {
    return a * a;
}

template <typename T>
T gcd(T a, T b) {
    if (a > b) return gcd(b, a);
    return a == 0 ? b : gcd(b % a, a);
}

template <typename T, typename U>
T mypow(T b, U n) {
    if (n == 0) return 1;
    if (n == 1) return b /* % MOD */;
    if (n % 2 == 0) {
        return mypow(b * b /* % MOD */, n / 2);
    } else {
        return mypow(b, n - 1) * b /* % MOD */;
    }
}

ll pcnt(ll b) {
    return __builtin_popcountll(b);
}

/* v-v-v-v-v-v-v-v-v Main Part v-v-v-v-v-v-v-v-v */

const int INF = 1 << 20;
const int dx[4] = {-1, 0, 0, 1};
const int dy[4] = {0, -1, 1, 0};

struct coo {
    int x;
    int y;
};

int main() {
    int H, W, K;
    cin >> H >> W >> K;

    string S[H];
    coo s;
    for (int x = 0; x < H; ++x) {
        cin >> S[x];
        for (int y = 0; y < W; ++y) {
            if (S[x][y] == 'S') {
                s = {x, y};
            }
        }
    }

    int d[H][W];
    fill(d[0], d[H], INF);

    queue<coo> que;
    que.push(s);
    d[s.x][s.y] = 0;

    // 壁を避けてK回移動
    while (!que.empty()) {
        coo v = que.front();
        que.pop();

        // K回以内で出られる場合
        if (v.x == 0 || v.x == H - 1 || v.y == 0 || v.y == W - 1) {
            cout << 1 << endl;
            return 0;
        }

        if (d[v.x][v.y] == K) continue;

        for (int i = 0; i < 4; ++i) {
            coo sv = {v.x + dx[i], v.y + dy[i]};
            // 境界外なら上で弾かれている
            if (S[sv.x][sv.y] == '#' || d[sv.x][sv.y] < INF) continue;
            d[sv.x][sv.y] = d[v.x][v.y] + 1;
            que.push(sv);
        }
    }

    // 外までの最短距離
    int mi = INF;
    for (int x = 0; x < H; ++x) {
        for (int y = 0; y < W; ++y) {
            if (d[x][y] == INF) continue;
            mi = min(mi, min(x, H - x - 1));
            mi = min(mi, min(y, W - y - 1));
        }
    }

    cout << (mi + K - 1) / K + 1 << endl;
    return 0;
}


Measured memory_bytes: 3584