#include <bits/stdc++.h>
using namespace std;
const int N = 805;
int dis[N][N];
char g[N][N];

int dx[] = { 0, 0, -1, 1 };
int dy[] = { 1, -1, 0, 0 };
int R, C, K;
vector<int> v;
void bfs(int x, int y) {

	dis[x][y] = 0;
	queue<pair<int, int> > q;
	q.push( { x, y });
	int T = min(x, min(R - x - 1, min(C - y - 1, y)));
	v.push_back((T + K - 1) / K);
	while (!q.empty()) {
		x = q.front().first;
		y = q.front().second;
		q.pop();
		if (dis[x][y] == K) continue;
		for (int i = 0; i < 4; i++) {
			int tx = dx[i] + x;
			int ty = dy[i] + y;
			if (tx < 0 || tx >= R || ty < 0 || ty >= C || dis[tx][ty] != -1
					|| g[tx][ty] != '.') continue;
			dis[tx][ty] = dis[x][y] + 1;
			int T = min(tx, min(R - tx - 1, min(C - ty - 1, ty)));
			v.push_back((T + K - 1) / K);
			q.push( { tx, ty });
		}
	}
}

int main() {

//	freopen("readin.txt", "r", stdin);

	scanf("%d%d%d", &R, &C, &K);
	int sx, sy;
	for (int i = 0; i < R; i++) {
		for (int j = 0; j < C; j++) {
			scanf(" %c", &g[i][j]);
			if (g[i][j] == 'S') {
				sx = i, sy = j;
			}
		}
	}
	memset(dis, -1, sizeof dis);
	bfs(sx, sy);
	sort(v.begin(), v.end());
	cout << v[0] + 1 << endl;

	return 0;
}
