#include <bits/stdc++.h>
using namespace std;
const int INF = 0x3f3f3f3f, maxn = 804;
queue<int> q;
int a[maxn][maxn], n, m, k, vis[maxn][maxn], sx, sy, mina;
int lrud[5] = {0, 1, 0, -1, 0};
void bfs() {
  int i;
  vis[sx][sy] = 0;
  q.push(sx);
  q.push(sy);
  while (!q.empty()) {
    int x = q.front();
    q.pop();
    int y = q.front();
    q.pop();
    if (vis[x][y] == k) continue;
    for (i = 1; i <= 4; i++) {
      int gx = x + lrud[i - 1];
      int gy = y + lrud[i];
      if (gx < 1 || gy < 1 || gx > n || gy > m ||
          vis[x][y] + 1 >= vis[gx][gy] || a[gx][gy] == 1)
        continue;
      vis[gx][gy] = vis[x][y] + 1;
      q.push(gx);
      q.push(gy);
    }
  }
}
int main() {
  int i, j, ans = 0;
  cin >> n >> m >> k;
  for (i = 1; i <= n; i++) {
    for (j = 1; j <= m; j++) {
      vis[i][j] = INF;
      char c;
      cin >> c;
      if (c == '.')
        a[i][j] = 0;
      else if (c == '#')
        a[i][j] = 1;
      else {
        sx = i, sy = j;
        a[i][j] = 0;
      }
    }
  }
  mina = INF;
  bfs();
  for (i = 1; i <= n; i++) {
    for (j = 1; j <= m; j++) {
      if (vis[i][j] != INF) {
        mina = min(
            mina,
            min((i + k - 2) / k + 1,
                min((j + k - 2) / k + 1,
                    min((n - i + k - 1) / k + 1, (m - j + k - 1) / k) + 1)));
      }
    }
  }
  cout << mina;
  return 0;
}
