#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;

#define ran 888

const int go[4][2] = {0, 1, 1, 0, 0, -1, -1, 0};

int n, m, k;
char s[ran][ran];
int d[ran][ran];
int q[ran*ran*2], l, r;

void bfs() {
	while(l<r) {
		int a = q[l++], b = q[l++];
		int dist = d[a][b];
		if(dist == k) continue;
		for(int i=0;i<4;i++) {
			int x = a+go[i][0], y = b+go[i][1];
			if(x<0 || x>=n || y<0 || y>=m) continue;
			if(s[x][y]=='#' || d[x][y]!=-1) continue;
			
			q[r++] = x;
			q[r++] = y;
			d[x][y] = dist + 1;
		}
	}
}

int calc(int x, int y) {
	int res = x+y;
	res = min(res, (x+k-1)/k);
	res = min(res, ((n-1-x) + (k-1))/k);
	res = min(res, (y+k-1)/k);
	res = min(res, ((m-1-y) + (k-1))/k);
	return res;
}

int main() {
	scanf("%d%d%d", &n, &m, &k);
	memset(d, -1, sizeof d);
	l=r=0;
	for(int i=0;i<n;i++) {
		scanf("%s", s[i]);
		for(int j=0;j<=m;j++)
			if(s[i][j]=='S') {
				q[r++] = i; q[r++] = j; d[i][j] = 0;
				s[i][j] = '.';
			}
	}
	bfs();
	
	int res = n+m;
	for(int i=0;i<n;i++)
		for(int j=0;j<m;j++)
			if(d[i][j]!=-1)
				res = min(res, calc(i, j) + 1);
	printf("%d\n", res);
	
	return 0;
}