#pragma GCC optimize ("O3")
#include "bits/stdc++.h"

using namespace std;
using ll = long long int;

#define debugos cout
#define debug(v) {printf("L%d %s > ",__LINE__,#v);debugos<<(v)<<endl;}
#define debugv(v) {printf("L%d %s > ",__LINE__,#v);for(auto e:(v)){debugos<<e<<" ";}debugos<<endl;}
#define debuga(m,w) {printf("L%d %s > ",__LINE__,#m);for(int x=0;x<(w);x++){debugos<<(m)[x]<<" ";}debugos<<endl;}
#define debugaa(m,h,w) {printf("L%d %s >\n",__LINE__,#m);for(int y=0;y<(h);y++){for(int x=0;x<(w);x++){debugos<<(m)[y][x]<<" ";}debugos<<endl;}}
#define ALL(v) (v).begin(),(v).end()
#define repeat(cnt,l) for(remove_reference<remove_const<decltype(l)>::type>::type cnt=0;(cnt)<(l);++(cnt))
#define rrepeat(cnt,l) for(auto cnt=(l)-1;0<=(cnt);--(cnt))
#define iterate(cnt,b,e) for(auto cnt=(b);(cnt)!=(e);++(cnt))
#define diterate(cnt,b,e) for(auto cnt=(b);(cnt)!=(e);--(cnt))
const ll MD = 1000000007ll; const long double PI = 3.1415926535897932384626433832795L;
inline void assert_call(bool assertion, function<void()> f) { if (!assertion) { cerr << "assertion fault:" << endl; f(); abort(); } }
template<typename T1, typename T2> inline ostream& operator <<(ostream &o, const pair<T1, T2> p) { o << '(' << p.first << ':' << p.second << ')'; return o; }
template<typename Vec> inline ostream& _ostream_vecprint(ostream& os, const Vec& a) {
    os << '['; for (const auto& e : a) os << ' ' << e << ' '; os << ']'; return os;
}
template<typename T> inline ostream& operator<<(ostream& o, const vector<T>& v) { return _ostream_vecprint(o, v); }
template<typename T, size_t S> inline ostream& operator<<(ostream& o, const array<T, S>& v) { return _ostream_vecprint(o, v); }
template<typename T> inline T& chmax(T& to, const T& val) { return to = max(to, val); }
template<typename T> inline T& chmin(T& to, const T& val) { return to = min(to, val); }
void bye(string s, int code = 0) { cout << s << endl; exit(code); }
mt19937_64 randdev(8901016);
template<typename T> inline T rand(T l, T h) { return uniform_int_distribution<T>(l, h)(randdev); }
template<> inline double rand<double>(double l, double h) { return uniform_real_distribution<double>(l, h)(randdev); }
template<> inline float rand<float>(float l, float h) { return uniform_real_distribution<float>(l, h)(randdev); }

#if defined(_WIN32) || defined(_WIN64)
#define getchar_unlocked _getchar_nolock
#define putchar_unlocked _putchar_nolock
#elif defined(__GNUC__)
#else
#define getchar_unlocked getchar
#define putchar_unlocked putchar
#endif
namespace {
#define isvisiblechar(c) (0x21<=(c)&&(c)<=0x7E)
    class MaiScanner {
    public:
        template<typename T> void input_integer(T& var) {
            var = 0; T sign = 1;
            int cc = getchar_unlocked();
            for (; cc < '0' || '9' < cc; cc = getchar_unlocked())
                if (cc == '-') sign = -1;
            for (; '0' <= cc && cc <= '9'; cc = getchar_unlocked())
                var = (var << 3) + (var << 1) + cc - '0';
            var = var * sign;
        }
        inline int c() { return getchar_unlocked(); }
        inline MaiScanner& operator>>(int& var) { input_integer<int>(var); return *this; }
        inline MaiScanner& operator>>(long long& var) { input_integer<long long>(var); return *this; }
        inline MaiScanner& operator>>(string& var) {
            int cc = getchar_unlocked();
            for (; !isvisiblechar(cc); cc = getchar_unlocked());
            for (; isvisiblechar(cc); cc = getchar_unlocked())
                var.push_back(cc);
            return *this;
        }
        template<typename IT> void in(IT begin, IT end) { for (auto it = begin; it != end; ++it) *this >> *it; }
    };
    class MaiPrinter {
    public:
        template<typename T>
        void output_integer(T var) {
            if (var == 0) { putchar_unlocked('0'); return; }
            if (var < 0)
                putchar_unlocked('-'),
                var = -var;
            char stack[32]; int stack_p = 0;
            while (var)
                stack[stack_p++] = '0' + (var % 10),
                var /= 10;
            while (stack_p)
                putchar_unlocked(stack[--stack_p]);
        }
        inline MaiPrinter& operator<<(char c) { putchar_unlocked(c); return *this; }
        inline MaiPrinter& operator<<(int var) { output_integer<int>(var); return *this; }
        inline MaiPrinter& operator<<(long long var) { output_integer<long long>(var); return *this; }
        inline MaiPrinter& operator<<(char* str_p) { while (*str_p) putchar_unlocked(*(str_p++)); return *this; }
        inline MaiPrinter& operator<<(const string& str) {
            const char* p = str.c_str();
            const char* l = p + str.size();
            while (p < l) putchar_unlocked(*p++);
            return *this;
        }
        template<typename IT> void join(IT begin, IT end, char sep = ' ') { for (bool b = 0; begin != end; ++begin, b = 1) b ? *this << sep << *begin : *this << *begin; }
    };
}
MaiScanner scanner;
MaiPrinter printer;

struct P {
    using T = int;
    T y, x;

    P(T _y = 0, T _x = 0) :y(_y), x(_x) {}

    inline bool operator == (P p) const { return y == p.y && x == p.x; }
    inline bool operator < (P p) const { return y == p.y ? x < p.x : y < p.y; }
    inline P operator+(P p) const { return P(y + p.y, x + p.x); }
    inline P operator-(P p) const { return P(y - p.y, x - p.x); }
    inline P operator+=(P p) { y += p.y; x += p.x; return *this; }
    inline P operator-=(P p) { y -= p.y; x -= p.x; return *this; }
};
inline ostream& operator<<(ostream& os, P p) { os << '(' << p.y << ',' << p.x << ')'; return os; }

const P FourMoving[] = { P(-1,0),P(0,1), P(1,0), P(0,-1) };
const P FiveMoving[] = { P(-1,0),P(0,1), P(1,0), P(0,-1), P(0,0) };
const P EightMoving[] = { P(-1,0),P(0,1), P(1,0), P(0,-1), P(-1,-1), P(-1,1), P(1,-1), P(1,1) };


//


int H, W, K, HW;
P start;

string A[801];
int dp[801][801];

int main() {
    scanner >> H >> W >> K; HW = H * W;
    repeat(i, H) {
        scanner >> A[i];
        repeat(j, W) {
            if (A[i][j] == 'S') {
                start.y = i;
                start.x = j;
                A[i][j] = '.';
                break;
            }
        }
    }

    fill(dp[0], dp[H], int(1e9));

    dp[start.y][start.x] = 0;

    queue<P> que;
    que.emplace(start);

    int best = 1e9;

    while (!que.empty()) {
        P p = que.front();
        que.pop();

        if (p.y == 0 || p.x == 0 || p.y == H - 1 || p.x == W - 1) {
            break;
        }

        int currcost = dp[p.y][p.x];
        
        for (auto mv : FourMoving) {
            P p2 = p + mv;
            int c = currcost + 1;
            if (A[p2.y][p2.x] == '#') continue;

            if (dp[p2.y][p2.x] > c) {
                dp[p2.y][p2.x] = c;
                que.push(p2);
            }
        }
    }

    repeat(i, H) {
        repeat(j, W) {
            if (dp[i][j] > K) continue;
            int m = min(min(min(H - i - 1, i), W - j - 1), j);
            chmin(best, 1 + (m+(K)-1)/(K));
        }
    }

    cout << best << endl;

    


    return 0;
}

Measured memory_bytes: 3584