#include <iostream>
#include <cstdio>
#include <queue>
using namespace std;

int h, w, k, mn=1e9, d[805][805];
char a[805][805];
queue<pair<int,int>> qu;
int dr[4]={1, 0, -1, 0};
int dc[4]={0, 1, 0, -1};

int main() {
	int i, j, r, c, tr, tc;
	cin >> h >> w >> k;
	for(i=0; i<h; i++) {
		cin >> a[i];
		for(j=0; j<w; j++) {
			d[i][j] = -1;
			if(a[i][j]=='S') {
				d[i][j] = 0;
				qu.push({i, j});
			}
		}
	}
	while(!qu.empty()) {
		r = qu.front().first;
		c = qu.front().second;
		qu.pop();
		mn = min(mn, min(r,c));
		mn = min(mn, min(h-1-r, w-1-c));
		if(0<r && r<h-1 && 0<c && c<w-1 && d[r][c]<k) {
			for(i=0; i<4; i++) {
				tr = r + dr[i];
				tc = c + dc[i];
				if(a[tr][tc]!='#' && d[tr][tc]==-1) {
					d[tr][tc] = d[r][c] + 1;
					qu.push({tr, tc});
				}
			}
		}
	}
	cout << (mn+k-1)/k + 1;
	return 0;
}