#include<bits/stdc++.h>

using namespace std;

using int64 = long long;
const int mod = 1e9 + 7;
// const int mod = 998244353;

const int64 infll = (1LL << 62) - 1;
const int inf = (1 << 30) - 1;

struct IoSetup {
  IoSetup() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(10);
    cerr << fixed << setprecision(10);
  }
} iosetup;


template< typename T1, typename T2 >
ostream &operator<<(ostream &os, const pair< T1, T2 > &p) {
  os << p.first << " " << p.second;
  return os;
}

template< typename T1, typename T2 >
istream &operator>>(istream &is, pair< T1, T2 > &p) {
  is >> p.first >> p.second;
  return is;
}

template< typename T >
ostream &operator<<(ostream &os, const vector< T > &v) {
  for(int i = 0; i < (int) v.size(); i++) {
    os << v[i] << (i + 1 != v.size() ? " " : "");
  }
  return os;
}

template< typename T >
istream &operator>>(istream &is, vector< T > &v) {
  for(T &in : v) is >> in;
  return is;
}

template< typename T1, typename T2 >
inline bool chmax(T1 &a, T2 b) { return a < b && (a = b, true); }

template< typename T1, typename T2 >
inline bool chmin(T1 &a, T2 b) { return a > b && (a = b, true); }

template< typename T = int64 >
vector< T > make_v(size_t a) {
  return vector< T >(a);
}

template< typename T, typename... Ts >
auto make_v(size_t a, Ts... ts) {
  return vector< decltype(make_v< T >(ts...)) >(a, make_v< T >(ts...));
}

template< typename T, typename V >
typename enable_if< is_class< T >::value == 0 >::type fill_v(T &t, const V &v) {
  t = v;
}

template< typename T, typename V >
typename enable_if< is_class< T >::value != 0 >::type fill_v(T &t, const V &v) {
  for(auto &e : t) fill_v(e, v);
}

template< typename F >
struct FixPoint : F {
  FixPoint(F &&f) : F(forward< F >(f)) {}

  template< typename... Args >
  decltype(auto) operator()(Args &&... args) const {
    return F::operator()(*this, forward< Args >(args)...);
  }
};

template< typename F >
inline decltype(auto) MFP(F &&f) {
  return FixPoint< F >{forward< F >(f)};
}


int grid_bfs(vector< string > &s, char start, int gy, int gx, const string &wall, int K) {
  const int vx[] = {0, 1, 0, -1}, vy[] = {1, 0, -1, 0};
  vector< vector< vector< pair< int, int > > > > min_cost(5, vector< vector< pair< int, int > > >(s.size(), vector< pair< int, int > >(s[0].size(), make_pair(inf, inf))));
  using pi = tuple< int, int, int, int, int >;
  priority_queue< pi, vector< pi >, greater<> > que;
  for(int i = 0; i < s.size(); i++) {
    for(int j = 0; j < s[i].size(); j++) {
      if(s[i][j] == start) {
        que.emplace(1, 0, i, j, 4);
        min_cost[4][i][j] = {1, 0};
      }
    }
  }

  while(!que.empty()) {
    int latte, malta, y, x, d;
    tie(latte, malta, y, x, d) = que.top();
    que.pop();
    if(min_cost[d][y][x] < make_pair(latte, malta)) continue;
    if(y == gy && x == gx) return latte;

    if(d <= 3) {
      int ny = y + vy[d], nx = x + vx[d];
      if(nx < 0 || ny < 0 || nx >= s[0].size() || ny >= s.size()) {}
      else if(s[ny][nx] != '@' && malta < K && chmin(min_cost[d][ny][nx], make_pair(latte, malta + 1))) {
        que.emplace(latte, malta + 1, ny, nx, d);
      }
      if(chmin(min_cost[4][y][x], make_pair(latte + 1, 0))) {
        que.emplace(latte + 1, 0, y, x, 4);
      }
    } else {
      for(int i = 0; i < 4; i++) {
        int ny = y + vy[i], nx = x + vx[i];
        if(nx < 0 || ny < 0 || nx >= s[0].size() || ny >= s.size()) {}
        else if(s[ny][nx] != '@' && malta < K && chmin(min_cost[i][ny][nx], make_pair(latte, malta + 1))) {
          que.emplace(latte, malta + 1, ny, nx, i);
        }
      }
    }
  }
  return -1;
}


int main() {
  int H, W, K;
  cin >> H >> W >> K;
  int a, b, c, d;
  cin >> a >> b >> c >> d;
  --a, --b, --c, --d;
  auto A = make_v< string >(H);
  cin >> A;
  A[a][b] = 'x';
  cout << grid_bfs(A, 'x', c, d, "@", K) << "\n";
}



Measured memory_bytes: 59128