//#define _GLIBCXX_DEBUG

#include<bits/stdc++.h>
using namespace std;

#define endl '\n'
#define lfs cout<<fixed<<setprecision(10)
#define ALL(a)  (a).begin(),(a).end()
#define ALLR(a)  (a).rbegin(),(a).rend()
#define spa << " " <<
#define fi first
#define se second
#define MP make_pair
#define MT make_tuple
#define PB push_back
#define EB emplace_back
#define rep(i,n,m) for(ll i = (n); i < (ll)(m); i++)
#define rrep(i,n,m) for(ll i = (ll)(m) - 1; i >= (ll)(n); i--)
using ll = int;
using ld = long double;
const ll MOD1 = 1e9+7;
const ll MOD9 = 998244353;
const ll INF = 1e9;
using P = pair<ll, ll>;
template<typename T1, typename T2>
bool chmin(T1 &a,T2 b){if(a>b){a=b;return true;}else return false;}
template<typename T1, typename T2>
bool chmax(T1 &a,T2 b){if(a<b){a=b;return true;}else return false;}
ll median(ll a,ll b, ll c){return a+b+c-max({a,b,c})-min({a,b,c});}
void ans1(bool x){if(x) cout<<"Yes"<<endl;else cout<<"No"<<endl;}
void ans2(bool x){if(x) cout<<"YES"<<endl;else cout<<"NO"<<endl;}
void ans3(bool x){if(x) cout<<"Yay!"<<endl;else cout<<":("<<endl;}
template<typename T1,typename T2>
void ans(bool x,T1 y,T2 z){if(x)cout<<y<<endl;else cout<<z<<endl;}  
template<typename T>
void debug(vector<vector<T>>&v,ll h,ll w){for(ll i=0;i<h;i++)
{cout<<v[i][0];for(ll j=1;j<w;j++)cout spa v[i][j];cout<<endl;}};
void debug(vector<string>&v,ll h,ll w){for(ll i=0;i<h;i++)
{for(ll j=0;j<w;j++)cout<<v[i][j];cout<<endl;}};
template<typename T>
void debug(vector<T>&v,ll n){if(n!=0)cout<<v[0];
for(ll i=1;i<n;i++)cout spa v[i];cout<<endl;};
template<typename T>
vector<vector<T>>vec(ll x, ll y, T w){
  vector<vector<T>>v(x,vector<T>(y,w));return v;}
ll gcd(ll x,ll y){ll r;while(y!=0&&(r=x%y)!=0){x=y;y=r;}return y==0?x:y;}
vector<ll>dx={1,-1,0,0,1,1,-1,-1};
vector<ll>dy={0,0,1,-1,1,-1,1,-1};
template<typename T>
vector<T> make_v(size_t a,T b){return vector<T>(a,b);}
template<typename... Ts>
auto make_v(size_t a,Ts... ts){
  return vector<decltype(make_v(ts...))>(a,make_v(ts...));
}
template<typename T1, typename T2>
ostream &operator<<(ostream &os, const pair<T1, T2>&p){
  return os << p.first << " " << p.second;
}
//mt19937 mt(chrono::steady_clock::now().time_since_epoch().count());
struct z{
  ll x,y,d;
  z(ll a,ll b,ll c):x(a),y(b),d(c){};
};
int main(){
  cin.tie(nullptr);
  ios_base::sync_with_stdio(false);
  ll res=0,buf=0;
  bool judge = true;
  int h,w,k;cin>>h>>w>>k;
  int x1,y1,x2,y2;cin>>x1>>y1>>x2>>y2;
  x1--;y1--;x2--;y2--;
  vector<string>a(h);
  rep(i,0,h)cin>>a[i];
  auto v=make_v(h,w,4,MP(0,0));
  rep(i,0,h)rep(j,0,w)rep(o,0,4){
    int x=i+dx[o],y=j+dy[o];
    if(x<0||y<0||x>=h||y>=w)x=-1,y=-1;
    v[i][j][o]=MP(x,y);
  }
  queue<z>que;
  que.emplace(x1,y1,0);
  auto dist=vec(h,w,INF);
  auto used=vec(h,w,false);
  //rep(i,0,h)rep(j,0,w)rep(o,0,4)cout<<i spa j spa o spa v[i][j][o]<<endl;
  
  while(!que.empty()){
    auto p=que.front();
    que.pop();
    if(dist[p.x][p.y]!=INF)continue;
    dist[p.x][p.y]=p.d;
    rep(i,0,4){
      P q=MP(p.x,p.y);
      P nxt=q;
      while(1){
        auto t=v[nxt.fi][nxt.se][i];
        nxt=t;
        if(t.fi==-1||a[t.fi][t.se]=='@'||abs(t.fi-p.x)+abs(t.se-p.y)>k)break;
      }
      while(1){
        auto t=v[q.fi][q.se][i];
        v[q.fi][q.se][i]=nxt;
        if(t.fi==-1||a[t.fi][t.se]=='@'||abs(t.fi-p.x)+abs(t.se-p.y)>k)break;
        if(used[t.fi][t.se]){
          q=t;
          continue;
        }
        used[t.fi][t.se]=true;
        q=t;
        que.emplace(t.fi,t.se,p.d+1);
      }
    }
  }
  //debug(dist,h,w);
  ans(dist[x2][y2]==INF,-1,dist[x2][y2]);
  return 0;
}

Measured memory_bytes: 144964