#include <cmath>
#include <queue>
#include <string>
#include <vector>
#include <iomanip>
#include <iostream>
#include <algorithm>
#include <functional>
#pragma warning(disable : 4996)
using namespace std;
const int inf = 1012345678;
int dir[] = { 0, 1, 0, -1 };
int H, W, K, sx, sy, d[809][809]; string s[809];
int main() {
	cin >> H >> W >> K;
	for (int i = 0; i < H; i++) cin >> s[i];
	for (int i = 0; i < H; i++) {
		for (int j = 0; j < W; j++) {
			if (s[i][j] == 'S') sx = i, sy = j;
			d[i][j] = inf;
		}
	}
	queue<pair<int, int> > que; que.push(make_pair(sx, sy)); d[sx][sy] = 0;
	int ret = inf;
	while (!que.empty()) {
		pair<int, int> u = que.front(); que.pop();
		int z = min({ u.first, H - u.first - 1, u.second, W - u.second - 1 });
		ret = min(ret, (z + K - 1) / K + 1);
		int r = d[u.first][u.second];
		if (r < K) {
			for (int i = 0; i < 4; i++) {
				int tx = u.first + dir[i], ty = u.second + dir[i ^ 1];
				if (0 <= tx && tx < H && 0 <= ty && ty < W && d[tx][ty] == inf && s[tx][ty] != '#') {
					d[tx][ty] = r + 1;
					que.push(make_pair(tx, ty));
				}
			}
		}
	}
	printf("%d\n", ret);
	return 0;
}