#include <algorithm>
#include <cassert>
#include <cfloat>
#include <climits>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <deque>
#include <iostream>
#include <iterator>
#include <limits>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <tuple>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

#define FOR(i,k,n) for(int(i)=(k);(i)<(n);++(i))
#define rep(i,n) FOR(i,0,n)
#define all(v) begin(v),end(v)
#ifdef ONLINE_JUDGE
  #define debug(x)
  #define debug2(x,y)
  #define debug3(x,y,z)
  #define assert(e) if(!(e)){stod("");}
#else
  #define debug(x) std::cerr<<#x<<": "<<x<<"\n"
  #define debug2(x,y) std::cerr<<#x<<": "<<x<<", "<<#y<<": "<<y<<"\n"
  #define debug3(x,y,z) std::cerr<<#x<<": "<<x<<", "<<#y<<": "<<y<<", "<<#z<<": "<<z<<"\n"
#endif

using ll=long long;
using vi=std::vector<int>;
using vvi=std::vector<vi>;
using vll=std::vector<ll>;
using vvll=std::vector<vll>;
template<typename T> using vvec=std::vector<std::vector<T>>;
template<typename T>
auto make_v(size_t sz){return std::vector<T>(sz);}
template<typename T,typename... Ts>
auto make_v(size_t sz,Ts...ts){return std::vector<decltype(make_v<T>(ts...))>(sz,make_v<T>(ts...));}
template<typename T>
void fill_v(T&var,const T&x){var=x;}
template<typename V,typename T>
void fill_v(V&v,const T&x){for(auto&& w:v){fill_v(w,x);}}

template<typename T> std::ostream& operator<<(std::ostream&s,const std::vector<T>&v){
  int sz=v.size();s<<"\n";rep(i,sz){s<<v[i];if(i<sz-1){s<<"\t";}}s<<"\n";return s;}
template<typename T> std::ostream& operator<<(std::ostream&s,const std::vector<std::vector<T>>&v){
  for(auto&& w:v){s<<w;}return s;}
template<typename T> std::ostream& operator<<(std::ostream&s,const std::deque<T>&v){
  int sz=v.size();s<<"\n";rep(i,sz){s<<v[i];if(i<sz-1){s<<"\t";}}s<<"\n";return s;}
template<typename T> std::ostream& operator<<(std::ostream&s,const std::deque<std::deque<T>>&v){
  for(auto&& w:v){s<<w;}return s;}
template<typename T> std::ostream& operator<<(std::ostream&s, const std::set<T>&v){
  s<<"\n";for(auto&& elm:v){s<<elm<<"\t";}s<<"\n";return s;}

inline void scan(int&a){scanf("%d",&a);}
inline void scan(ll&a){scanf("%lld",&a);}
inline void scan(char&a){scanf(" %c",&a);}
inline void scan(double&a){scanf("%lf",&a);}
template<typename T>
inline void scan(std::vector<T>&v){for(auto&& sv:v){scan(sv);}}
template<typename First,typename...Args>
inline void scan(First&f,Args&...args){scan(f);scan(args...);}
inline void scan(std::string&s){char BUF[3000000];scanf(" %s",BUF);s=std::string(BUF);}
inline void print(int a){printf("%d\n",a);}
inline void print(ll a){printf("%lld\n",a);}
inline void print(double a){printf("%.12f\n",a);}
inline void print(std::string s){std::cout<<s<<"\n";}

using namespace std;

vi dx = {0, 1,  0, -1};
vi dy = {1, 0, -1,  0};

struct Node {
  ll cost, cost_fraction, x, y, dir;
  bool operator >(const Node& b) const {
    return vll{cost, cost_fraction, x, y, dir} > vll{b.cost, b.cost_fraction, b.x, b.y, b.dir};
  }
};

struct Cost {
  int cost, cost_fraction;
};

void solve() {
  int h, w, k;
  scan(h, w, k);
  priority_queue<Node, vector<Node>, greater<Node>> q;
  int x1, y1, x2, y2;
  scan(x1, y1, x2, y2);
  x1 -= 1; y1 -= 1; x2 -= 1; y2 -= 1;
  vvi board(h, vi(w, 0));
  rep (i, h) {
    char tmp;
    rep (j, w) {
      scan(tmp);
      if (tmp == '@') {
        board[i][j] = 1;
      }
    }
  }
  // end of inputs
  ll base = 1e7;
  vector<vector<vll>> costs(h, vvll(w, vll(4, base * base)));
  rep (k, 4) {
    costs[x1][y1][k] = 0;
    q.push(Node{0, 0, x1, y1, k});
  }
  while (!q.empty()) {
    auto node = q.top();
    q.pop();
    debug2(node.x, node.y);
    ll cost = node.cost * base + node.cost_fraction;
    if (costs[node.x][node.y][node.dir] < cost) {
      continue;
    }
    ll next_cost = node.cost + ((node.cost_fraction > 0) ? 1 : 0);
    next_cost *= base;
    rep (k, 4) {
      if (costs[node.x][node.y][k] <= next_cost) {
        continue;
      }
      costs[node.x][node.y][k] = next_cost;
      q.push(Node{next_cost / base, next_cost % base, node.x, node.y, k});
    }
    //debug("hoge");
    if (node.cost_fraction == k-1) {
      next_cost = (node.cost + 1) * base;
    } else {
      next_cost = node.cost * base + node.cost_fraction + 1;
    }
    //debug("fuga");
    int next_x = node.x + dx[node.dir];
    int next_y = node.y + dy[node.dir];
    if (next_x < 0 || h <= next_x || next_y < 0 || w <= next_y) {
      continue;
    }
    if (board[next_x][next_y] == 1) {
      continue;
    }
    if (costs[next_x][next_y][node.dir] <= next_cost) {
      continue;
    }
    //debug("piyo");
    costs[next_x][next_y][node.dir] = next_cost;
    q.push(Node{next_cost / base, next_cost % base, next_x, next_y, node.dir});
  }
  ll ans_cost = base * base;
  rep (k, 4) {
    ans_cost = min(ans_cost, costs[x2][y2][k]);
  }
  if (ans_cost == base * base) {
    print(-1);
    return;
  }
  ll ans = ans_cost / base + ((ans_cost % base > 0) ? 1 : 0);
  print(ans);
}

int main() {
  solve();
  return 0;
}


Measured memory_bytes: 147348