#include <bits/stdc++.h>
using namespace std;
int h, w, k;
const int INF = 1e9;
const int N = 850;
string A[N]; int vis[N][N];
int ans = INF; queue <int> Q;
int check(int i, int j)
{
    return ans = min(ans, (min(min(i, h - 1 - i), min(j, w - 1 - j)) + k - 1) / k + 1);
}
int main()
{
    cin >> h >> w >> k;
    for (int i = 0; i < h; ++ i)
        cin >> A[i];
    for (int i = 0; i < h; ++ i)
        for (int j = 0; j < w; ++ j)
            if (A[i][j] == 'S')
                Q.push(i), Q.push(j), Q.push(k),
                vis[i][j] = 1;
    while (!Q.empty())
    {
        int i = Q.front(); Q.pop();
        int j = Q.front(); Q.pop();
        int k = Q.front(); Q.pop();
        if (check(i, j) == 1) break;
        if (k == 0) continue;
        for (int di = -1; di <= 1; ++ di)
            for (int dj = -1; dj <= 1; ++ dj)
                if (abs(di) + abs(dj) == 1) if (A[i + di][j + dj] == '.' && !vis[i + di][j + dj])
                    Q.push(di + i), Q.push(dj + j), Q.push(k - 1),
                    vis[i + di][j + dj] = 1;
    }

    cout << ans << endl;
}
