#define MOD_TYPE 1

#pragma region Macros
#include <bits/stdc++.h>
using namespace std;
/*
#include <boost/multiprecision/cpp_int.hpp>
#include <boost/multiprecision/cpp_dec_float.hpp>
using multiInt = boost::multiprecision::cpp_int;
using lld = boost::multiprecision::cpp_dec_float_100;
*/
/*
#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
*/
using ll = long long int;
using ld = long double;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using pld = pair<ld, ld>;
template <typename Q_type>
using smaller_queue = priority_queue<Q_type, vector<Q_type>, greater<Q_type>>;

constexpr ll MOD = (MOD_TYPE == 1 ? (ll)(1e9 + 7) : 998244353);
//constexpr ll MOD = 1;
constexpr int INF = (int)1e9;
constexpr ll LINF = (ll)4e18;
constexpr double PI = acos(-1.0);
constexpr double EPS = 1e-10;
constexpr int Dx[] = {0, 0, -1, 1, -1, 1, -1, 1, 0};
constexpr int Dy[] = {1, -1, 0, 0, -1, -1, 1, 1, 0};

#define REP(i, m, n) for (ll i = m; i < (ll)(n); ++i)
#define rep(i, n) REP(i, 0, n)
#define REPI(i, m, n) for (int i = m; i < (int)(n); ++i)
#define repi(i, n) REPI(i, 0, n)
#define MP make_pair
#define MT make_tuple
#define YES(n) cout << ((n) ? "YES" : "NO") << "\n"
#define Yes(n) cout << ((n) ? "Yes" : "No") << "\n"
#define possible(n) cout << ((n) ? "possible" : "impossible") << "\n"
#define Possible(n) cout << ((n) ? "Possible" : "Impossible") << "\n"
#define Yay(n) cout << ((n) ? "Yay!" : ":(") << "\n"
#define all(v) v.begin(), v.end()
#define NP(v) next_permutation(all(v))
#define dbg(x) cerr << #x << ":" << x << "\n";

inline void init_main()
{
  cin.tie(0);
  ios::sync_with_stdio(false);
  cout << setprecision(30) << setiosflags(ios::fixed);
}
template <typename T>
inline bool chmin(T &a, T b)
{
  if (a > b)
  {
    a = b;
    return true;
  }
  return false;
}
template <typename T>
inline bool chmax(T &a, T b)
{
  if (a < b)
  {
    a = b;
    return true;
  }
  return false;
}
inline ll CEIL(ll a, ll b)
{
  return (a + b - 1) / b;
}
template <typename A, size_t N, typename T>
inline void Fill(A (&array)[N], const T &val)
{
  fill((T *)array, (T *)(array + N), val);
}
template <typename T, typename U>
constexpr ostream &operator<<(ostream &os, pair<T, U> &p) noexcept
{
  os << p.first << " " << p.second;
  return os;
}
#pragma endregion

void solve()
{
  int h, w, k;
  cin >> h >> w >> k;
  int x1, y1, x2, y2;
  cin >> x1 >> y1 >> x2 >> y2;
  x1--, y1--, x2--, y2--;
  vector<vector<char>> s(h, vector<char>(w));
  rep(i, h) rep(j, w) cin >> s[i][j];
  queue<pii> que;
  que.push(MP(x1, y1));
  vector<vector<int>> d(h, vector<int>(w, INF));
  d[x1][y1] = 0;
  while (!que.empty())
  {
    auto [i, j] = que.front();
    que.pop();
    // 上
    for (int ii = i - 1, jj = j, cnt = 0; ii >= 0 and cnt < k; ii--, cnt++)
    {
      if (d[ii][jj] == d[i][j] + 1)
        continue;
      if (d[ii][jj] != INF or s[ii][jj] == '@')
        break;
      d[ii][jj] = d[i][j] + 1;
      que.push(MP(ii, jj));
    }
    // 下
    for (int ii = i + 1, jj = j, cnt = 0; ii < h and cnt < k; ii++, cnt++)
    {
      if (d[ii][jj] == d[i][j] + 1)
        continue;
      if (d[ii][jj] != INF or s[ii][jj] == '@')
        break;
      d[ii][jj] = d[i][j] + 1;
      que.push(MP(ii, jj));
    }
    // 左
    for (int ii = i, jj = j - 1, cnt = 0; jj >= 0 and cnt < k; jj--, cnt++)
    {
      if (d[ii][jj] == d[i][j] + 1)
        continue;
      if (d[ii][jj] != INF or s[ii][jj] == '@')
        break;
      d[ii][jj] = d[i][j] + 1;
      que.push(MP(ii, jj));
    }
    // 右
    for (int ii = i, jj = j + 1, cnt = 0; jj < w and cnt < k; jj++, cnt++)
    {
      if (d[ii][jj] == d[i][j] + 1)
        continue;
      if (d[ii][jj] != INF or s[ii][jj] == '@')
        break;
      d[ii][jj] = d[i][j] + 1;
      que.push(MP(ii, jj));
    }
  }
  cout << (d[x2][y2] == INF ? -1 : d[x2][y2]) << "\n";
}

int main()
{
  init_main();

  solve();

  return 0;
}


Measured memory_bytes: 12000