#include "bits/stdc++.h"
using namespace std;
typedef long long ll;
const ll MOD = 1e9 + 7;
const double PI = 3.141592653589793238;
const double EPS = 1e-10;
typedef pair<int, int> P;

string A[800];
int dist[800][800];
int dx[] = { 1,0,-1,0 };
int dy[] = { 0,1,0,-1 };

int main() {
	int H, W, K;
	cin >> H >> W >> K;
	int sx, sy;
	for (int i = 0; i < H; i++) {
		cin >> A[i];
		for (int j = 0; j < W; j++) {
			if (A[i][j] == 'S') sx = j, sy = i;
		}
	}
	memset(dist, -1, sizeof(dist));
	dist[sy][sx] = 0;
	queue<P> Q;
	Q.push(P(sx, sy));
	int ans = 1 << 30;
	while (!Q.empty()) {
		P p = Q.front(); Q.pop();
		int x = p.first, y = p.second;
		if (dist[y][x] > K) break;
		int d = min(x, W - 1 - x);
		d = min(d, y);
		d = min(d, H - 1 - y);
		ans = min(ans, 1 + (d + K - 1) / K);
		for (int i = 0; i < 4; i++) {
			int nx = x + dx[i];
			int ny = y + dy[i];
			if (0 > nx || nx >= W || 0 > ny || ny >= H || A[ny][nx] == '#' || dist[ny][nx] != -1) continue;
			dist[ny][nx] = dist[y][x] + 1;
			Q.push(P(nx, ny));
		}
	}
	cout << ans << endl;
}
