/* Headers */
#include <unordered_map>
#include <algorithm>
#include <iostream>
#include <cstring>
#include <climits>
#include <cstdio>
#include <cctype>
#include <vector>
#include <cmath>
#include <queue>
#include <stack>
#include <set>
#define FOR(i,a,b,c) for(int i=(a);i<=(b);i+=(c))
#define ROF(i,a,b,c) for(int i=(a);i>=(b);i-=(c))
#define FORL(i,a,b,c) for(long long i=(a);i<=(b);i+=(c))
#define ROFL(i,a,b,c) for(long long i=(a);i>=(b);i-=(c))
#define FORR(i,a,b,c) for(register int i=(a);i<=(b);i+=(c))
#define ROFR(i,a,b,c) for(register int i=(a);i>=(b);i-=(c))
#define RevEdge(x) x^1
#define lowbit(x) x&(-x)
#define LeftChild(x) x<<1
#define RightChild(x) (x<<1)+1
#define CLOSE_IN() fclose(stdin);
#define CLOSE_OUT() fclose(stdout);
#define FILE_IN(x) freopen(x,"r",stdin);
#define FILE_OUT(x) freopen(x,"w",stdout);
#define IOS(x) std::ios::sync_with_stdio(x)
#define Dividing() printf("-----------------------------------\n");
namespace FastIO {
#define gc() (iS == iT ? (iT = (iS = ibuff) + fread(ibuff, 1, SIZ, stdin), (iS == iT ? EOF : *iS++)) : *iS++)
    const int SIZ = 1 << 21 | 1;
    char* iS, * iT, ibuff[SIZ], obuff[SIZ], * oS = obuff, * oT = oS + SIZ - 1, fu[110], cc;
    int fr;
    inline void out() {
        fwrite(obuff, 1, oS - obuff, stdout);
        oS = obuff;
    }
    template<class Type>
    inline void read(Type& x) {
        x = 0;
        Type y = 1;
        for (cc = gc(); (cc > '9' || cc < '0') && cc != '-'; cc = gc());
        cc == '-' ? y = -1 : x = (cc & 15);
        for (cc = gc(); cc >= '0' && cc <= '9'; cc = gc())
            x = x * 10 + (cc & 15);
        x *= y;
    }
    template<class Type>
    inline void print(Type x, char text = '\n') {
        if (x < 0)
            * oS++ = '-', x *= -1;
        if (x == 0)
            * oS++ = '0';
        while (x)
            fu[++fr] = x % 10 + '0', x /= 10;
        while (fr);
            * oS++ = fu[fr--];
        * oS++ = text;
        out();
    }
    inline void prints(char x[], char text = '\n') {
        for (register int i = 0; x[i]; ++i)
            * oS++ = x[i];
        * oS++ = text;
        out();
    }
}
using namespace FastIO;
template<typename T>
inline T max(T a, T b) {return (a > b) ? a : b;}
template<typename T>
inline T min(T a, T b) {return (a > b) ? b : a;}
/* definitions */
const int dx[5] = {0, 0, 0, 1, -1};
const int dy[5] = {0, 1, -1, 0, 0};
const int MAXN = 8e2 + 10;
char squ[MAXN][MAXN];
int n, m, k, Dx, Dy;
int qx[MAXN * MAXN], qy[MAXN * MAXN], ql, qr, dis[MAXN][MAXN], ans;
/* functions */
int main(int argc, char *argv[]) {
    /*FILE_IN("data.in");*/ scanf("%d %d %d", &n, &m, &k); ans = n;
    FOR(i, 1, n, 1) {
        scanf("%s", squ[i] + 1);
        FOR(j, 1, m, 1) {
            dis[i][j] = -1;
            if(squ[i][j] == 'S') Dx = i, Dy = j;
        }
    } dis[Dx][Dy] = 0, ql = qr = 1, qx[1] = Dx, qy[1] = Dy;
    while(ql <= qr) {
        int x = qx[ql], y = qy[ql]; ++ql;
        int dist = std::min({x - 1, n - x, y - 1, m - y});
        ans = std::min(ans, 1 + (dist + k - 1) / k);
        if(dis[x][y] == k) continue;
        FOR(d, 1, 4, 1) {
            int nx = x + dx[d], ny = y + dy[d];
            if(nx < 1 || nx > n || ny < 1 || ny > m || squ[nx][ny] == '#' || ~dis[nx][ny]) continue;
            dis[nx][ny] = dis[x][y] + 1; ++qr, qx[qr] = nx, qy[qr] = ny;
        }
    } printf("%d\n", ans);
    return 0;
}


Measured memory_bytes: 11816