#include <bits/stdc++.h>
using namespace std;

struct P { int x, y; };

char A[800][800];
int used[800][800];

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

int main()
{
	int H, W, K;
	P s;
	cin >> H >> W >> K;
	for (int i = 0; i < H; i++) {
		for (int j = 0; j < W; j++) {
			cin >> A[i][j];
			if (A[i][j] == 'S') {
				s.x = i;
				s.y = j;
			}
		}
	}
	vector<P> q;
	q.push_back(s);
	used[s.x][s.y] = 1;
	int res = min(s.x, min(s.y, min(H - s.x - 1, W - s.y - 1)));
	for (int i = 0; i < K && !q.empty(); i++) {
		auto tmp = q; q.clear();
		for (auto p : tmp) {
			for (int j = 0; j < 4; j++) {
				int tx = p.x + dx[j], ty = p.y + dy[j];
				if (tx >= 0 && tx < H && ty >= 0 && ty < W && A[tx][ty] != '#' && used[tx][ty] == 0) {
					used[tx][ty] = 1;
					q.push_back((P){ tx, ty });
					res = min(res, min(tx, min(ty, min(H - tx - 1, W - ty - 1))));
				}
			}
		}
	}
	cout << ((res + K - 1) / K + 1) << endl;
	return 0;
}
