#include <iostream>
#include <string>
#include <queue>
using namespace std;
typedef pair<int, int> P;

const int INF = 10000000;

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

int d[803][803];

int main()
{
    int h, w, k;
    cin >> h >> w >> k;
    string a[803];
    for(int i = 0; i < h; i++){
        cin >> a[i];
    }
    queue<P> que;
    for(int i = 0; i < h; i++){
        for(int j = 0; j < w; j++){
            if(a[i][j] == 'S') que.push(P(i, j));
            else d[i][j] = -1;
        }
    }
    int ans = INF;
    while(que.size()){
        P p = que.front();
        que.pop();
        int x = p.first, y = p.second;
        for(int i = 0; i < 4; i++){
            int u = x + dx[i], v = y + dy[i];
            if(u >= 0 && u < h && v >= 0 && v < w && a[u][v] != '#' && d[u][v] == -1){
                d[u][v] = d[x][y] + 1;
                que.push(P(u, v));
            }
        }
        if(d[x][y] <= k){
            ans = min(ans, min(min(x + k - 1, y + k - 1), min(h - x + k - 2, w - y + k - 2)) / k + 1);
        }
    }
    cout << ans << endl;
}
