#include <bits/stdc++.h>

// #define int int64_t

const int kMaxT = 6e6 + 5, kMaxN = 3e3 + 5;

int n, m, k;
int sx, sy, tx, ty;
std::vector<std::pair<int, int>> G[kMaxT];
std::string s[kMaxN];

int getid(int x, int y) { return (x - 1) * m + y; }

void dijkstra(int s, int t) {
  static int dis[kMaxT];
  static bool vis[kMaxT];
  memset(dis, 0x3f, sizeof(dis));
  memset(vis, 0, sizeof(vis));
  std::priority_queue<std::pair<int, int>> q;
  if (::s[sx][sy] == '.') {
    dis[s] = 0, q.emplace(0, s);
  } else {
    for (auto [v, w] : G[s])
      dis[v] = w, q.emplace(-dis[v], v);
  }
  for (; !q.empty();) {
    int u = q.top().second; q.pop();
    // std::cerr << (u - 1) / m + 1 << ' ' << (u - 1) % m + 1 << ' ' << dis[u] << '\n';
    if (vis[u]) continue;
    vis[u] = 1;
    for (auto [v, w] : G[u]) {
      if (u == s && ::s[sx][sy] == '#' && !w) continue;
      if (dis[v] > dis[u] + w) {
        dis[v] = dis[u] + w;
        q.emplace(-dis[v], v);
      }
    }
  }
  std::cout << dis[t] << '\n';
}

void dickdreamer() {
  std::cin >> n >> m >> k >> sx >> sy >> tx >> ty;
  for (int i = 1; i <= n; ++i) {
    std::cin >> s[i];
    s[i] = " " + s[i];
  }
  for (int i = 1; i <= n; ++i) {
    for (int j = 1; j <= m; ++j) {
      if (i < n && s[i + 1][j] == '.') {
        G[getid(i, j)].emplace_back(getid(i + 1, j), 0);
      }
      if (j < m && s[i][j + 1] == '.') {
        G[getid(i, j)].emplace_back(getid(i, j + 1), 0);
      }
      if (i > 1 && s[i - 1][j] == '.') {
        G[getid(i, j)].emplace_back(getid(i - 1, j), 0);
      }
      if (j > 1 && s[i][j - 1] == '.') {
        G[getid(i, j)].emplace_back(getid(i, j - 1), 0);
      }
    }
  }
  for (int i = 1; i <= n; ++i) {
    for (int j = 1; j <= m; ++j) {
      for (int x = std::max(i - k, 1); x <= std::min(n, i + k); ++x) {
        for (int y = std::max(j - k, 1); y <= std::min(m, j + k); ++y) {
          if (std::min(abs(x - i), abs(y - j)) <= k - 1) {
            G[getid(i, j)].emplace_back(getid(x, y), 1);
          }
        }
      }
    }
  }
  dijkstra(getid(sx, sy), getid(tx, ty));
}

int32_t main() {
#ifdef ORZXKR
  freopen("in.txt", "r", stdin);
  freopen("out.txt", "w", stdout);
#endif
  std::ios::sync_with_stdio(0), std::cin.tie(0), std::cout.tie(0);
  int T = 1;
  // std::cin >> T;
  while (T--) dickdreamer();
  // std::cerr << 1.0 * clock() / CLOCKS_PER_SEC << "s\n";
  return 0;
}