#include "bits/stdc++.h"
using namespace std;
const int N = 805;
const int dx[4] = {0 , 1 , 0 , -1};
const int dy[4] = {1 , 0 , -1 , 0};
int n , m , k;
char str[N][N];
int dist[N][N];
pair < int , int > que[N * N];
int ql , qr;
int main(){
	scanf("%d %d %d" , &n , &m , &k);
	for(int i = 1 ; i <= n ; ++i){
		for(int j = 1 ; j <= m ; ++j){
			dist[i][j] = 1e9;
		}
	}
	for(int i = 1 ; i <= n ; ++i){
		scanf("%s" , str[i] + 1);
		for(int j = 1 ; j <= m ; ++j){
			if(str[i][j] == 'S'){
				que[qr++] = make_pair(i , j);
				dist[i][j] = 0;
			}
		}
	}
	while(ql < qr){
		int x = que[ql].first;
		int y = que[ql].second;
		++ql;
		for(int i = 0 ; i < 4 ; ++i){
			int nx = x + dx[i];
			int ny = y + dy[i];
			if(nx < 1 || ny < 1 || nx > n || ny > m){
				continue;
			}
			if(str[nx][ny] == '#'){
				continue;
			}
			if(dist[nx][ny] > dist[x][y] + 1){
				dist[nx][ny] = dist[x][y] + 1;
				que[qr++] = {nx , ny};
			}
		}
	}
	int ans = 1e9;
	for(int i = 1 ; i <= n ; ++i){
		for(int j = 1 ; j <= m ; ++j){
			if(dist[i][j] <= k){
				ans = min(ans , 1 + ((min(min(i - 1 , n - i) , min(j - 1 , m - j)) + k - 1) / k));
			}
		}
	}
	printf("%d\n" , ans);
}