#ifdef LOCAL
//    #define _GLIBCXX_DEBUG
//    #define __clock__
#else
    #pragma GCC optimize("Ofast")
#endif

#include<bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using VI = vector<ll>;
using VV = vector<VI>;
using VS = vector<string>;
using PII = pair<ll, ll>;

// tourist set
template <typename A, typename B>
string to_string(pair<A, B> p);

template <typename A, typename B, typename C>
string to_string(tuple<A, B, C> p);

template <typename A, typename B, typename C, typename D>
string to_string(tuple<A, B, C, D> p);

string to_string(const string& s) {
  return '"' + s + '"';
}

string to_string(const char* s) {
  return to_string((string) s);
}

string to_string(bool b) {
  return (b ? "true" : "false");
}

string to_string(vector<bool> v) {
  bool first = true;
  string res = "{";
  for (int i = 0; i < static_cast<int>(v.size()); i++) {
    if (!first) {
      res += ", ";
    }
    first = false;
    res += to_string(v[i]);
  }
  res += "}";
  return res;
}

template <size_t N>
string to_string(bitset<N> v) {
  string res = "";
  for (size_t i = 0; i < N; i++) {
    res += static_cast<char>('0' + v[i]);
  }
  return res;
}

template <typename A>
string to_string(A v) {
  bool first = true;
  string res = "{";
  for (const auto &x : v) {
    if (!first) {
      res += ", ";
    }
    first = false;
    res += to_string(x);
  }
  res += "}";
  return res;
}

template <typename A, typename B>
string to_string(pair<A, B> p) {
  return "(" + to_string(p.first) + ", " + to_string(p.second) + ")";
}

template <typename A, typename B, typename C>
string to_string(tuple<A, B, C> p) {
  return "(" + to_string(get<0>(p)) + ", " + to_string(get<1>(p)) + ", " + to_string(get<2>(p)) + ")";
}

template <typename A, typename B, typename C, typename D>
string to_string(tuple<A, B, C, D> p) {
  return "(" + to_string(get<0>(p)) + ", " + to_string(get<1>(p)) + ", " + to_string(get<2>(p)) + ", " + to_string(get<3>(p)) + ")";
}

void debug_out() { cerr << '\n'; }

template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
  cerr << " " << to_string(H);
  debug_out(T...);
}

#ifdef LOCAL
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#else
#define debug(...) 42
#endif
// tourist set end

template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }

#define FOR(i,a,b) for(ll i=(a);i<(b);++i)
#define rep(i,b) FOR(i, 0, b)
#define ALL(v) (v).begin(), (v).end()
#define p(s) cout<<(s)<<'\n'
#define p2(s, t) cout << (s) << " " << (t) << '\n'
#define br() p("")
#define pn(s) cout << (#s) << " " << (s) << '\n'
#define SZ(x) ((int)(x).size())
#define SORT(A) sort(ALL(A))
#define RSORT(A) sort(ALL(A), greater<ll>())
#define MP make_pair
#define p_yes() p("Yes")
#define p_no() p("No")

ll SUM(VI& V){
  return accumulate(ALL(V), 0LL);
}

ll MIN(VI& V){return *min_element(ALL(V));}
ll MAX(VI& V){return *max_element(ALL(V));}

void print_vector(VI& V){
  ll n = V.size();
  rep(i, n){
    if(i) cout << ' ';
    cout << V[i];
  }
  cout << endl;
}

ll gcd(ll a,ll b){
    if(b == 0) return a;
    return gcd(b,a%b);
}

ll lcm(ll a,ll b){
    ll g = gcd(a,b);
    return a / g * b;
}

// long double
using ld = long double;
#define EPS (1e-14)
#define equals(a,b) (fabs((a)-(b)) < EPS)

void no(){p_no(); exit(0);}
void yes(){p_yes(); exit(0);}

const ll mod = 1e9 + 7;
const ll inf = 1e18;
const double PI = acos(-1);

// 左・下・右・上
int dx[4] = {-1, 0, 1,  0};
int dy[4] = { 0, 1, 0, -1};

struct Node{
    PII distance; // {手数, 何歩使ったか}
    ll y;
    ll x;
    ll dir;
    Node(PII pa, ll _y, ll _x, ll _dir){
        distance = pa;
        y = _y;
        x = _x;
        dir = _dir;
    }
    Node(){}
 
    bool operator<(const Node &another) const
    {
        return distance < another.distance;
    }
    bool operator>(const Node &another) const
    {
        return distance > another.distance;
    }
    string ToString(){
      stringstream ss;
      ss << "d:" << distance.first << ' ' << "st:" << distance.second << ' ' << y << ' ' << x << ' ' << dir;
      return ss.str();
    }
};

using VB = vector<bool>;
using VP = vector<PII>;

ll H,W,K;
vector<vector<VB>> visited;
vector<vector<VP>> dist;
VS S;

bool in_range(ll i, ll j){
  if(0<=i && i<H && 0<=j && j<W){
    return true;
  }else{
    return false;
  }
}

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);

    // input
    cin>>H>>W>>K;
    
    ll x1,y1,x2,y2;
    //cin>>x1>>y1>>x2>>y2;
    cin>>y1>>x1>>y2>>x2;
    x1--;y1--;
    x2--;y2--;
    debug(x1,y1,x2,y2);

    visited.resize(H, vector<VB>(W, VB(4)));
    dist.resize(H, vector<VP>(W, VP(4, {inf,0LL})));

    S.resize(H);
    rep(i,H){
      cin>>S[i];
    }

    priority_queue<Node, vector<Node>, greater<Node>> que;
    rep(dir,4){
    //   que.push(Node({0,0}, y1, x1, dir)); 
      dist[y1][x1][dir] = {0,0};
    }
    que.push(Node({0,0}, y1, x1, -1));

    while(!que.empty()){
      auto node = que.top(); que.pop();
      // debug(node.ToString());

      rep(i,4){
        ll ny = node.y + dy[i];
        ll nx = node.x + dx[i];
        if(!in_range(ny, nx)) continue;
        if(S[ny][nx]=='@') continue;

        PII d;
        if(i!=node.dir){
          // 方向を変える
          d = {node.distance.first+1, 1};
        }else{
          // 方向を変えない
          if(node.distance.second==K){
            d = {node.distance.first+1, 1}; // 1手増える
          }else{
            d = node.distance; // 1歩増える
            d.second++;
          }
        }

        if(dist[ny][nx][i]>d){
          dist[ny][nx][i] = d;
          que.push(Node(d, ny, nx, i));
        }
      }
    }

    ll ans = inf;
    rep(dir,4){
      chmin(ans, dist[y2][x2][dir].first);
    }
    if(ans==inf){
      p(-1);
    }else{
      p(ans);
    }

    return 0;
}

Measured memory_bytes: 276824