//#pragma GCC optimize("Ofast")
//#pragma GCC optimize("unroll-loops")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using db = double;
using ld = long double;
template<typename T> using V = vector<T>;
template<typename T> using VV = vector<vector<T>>;
#define fs first
#define sc second
#define pb push_back
#define mp make_pair
#define mt make_tuple
#define eb emplace_back
#define lb lower_bound
#define ub upper_bound
#define all(v) (v).begin(),(v).end()
#define siz(v) (ll)(v).size()
#define rep(i,a,n) for(ll i=a;i<(ll)(n);++i)
#define repr(i,a,n) for(ll i=n-1;(ll)a<=i;--i)
#define ENDL '\n'
typedef pair<int,int> Pi;
typedef pair<ll,ll> PL;
constexpr ll mod = 1000000007;
constexpr ll INF = 1000000099;
constexpr ll LINF = (ll)(1e18 +99);
const vector<ll> dx={-1,1,0,0},dy={0,0,-1,1};
template<typename T,typename U> inline bool chmin(T& t, const U& u){if(t>u){t=u;return 1;}return 0;}
template<typename T,typename U> inline bool chmax(T& t, const U& u){if(t<u){t=u;return 1;}return 0;}
template<typename T> inline T gcd(T a,T b){return b?gcd(b,a%b):a;}

template<typename T,typename Y> inline T mpow(T a, Y n) {
  T res = 1;
  for(;n;n>>=1) {
    if (n & 1) res = res * a;
    a = a * a;
  }
  return res;
}

template<typename T,typename Y>
ostream& operator<<(ostream& os,const pair<T,Y>& p){
   return os<<"{"<<p.fs<<","<<p.sc<<"}";
}
template<typename T> ostream& operator<<(ostream& os,const V<T>& v){
   os<<"{";
  for(auto e:v)os<<e<<",";
  return os<<"}";
}
template<typename ...Args>
void debug(Args&... args){
  for(auto const& x:{args...}){
    cerr<<x<<' ';
  }
  cerr<<ENDL;
}



signed main(){
  cin.tie(0);cerr.tie(0);ios::sync_with_stdio(false);
  cout<<fixed<<setprecision(20);
  
  ll h,w,k;cin>>h>>w>>k;
  ll sg,sr,gg,gr;cin>>sg>>sr>>gg>>gr;
  sg--;sr--;gg--;gr--;

  V<string> v(h);
  rep(i,0,h)cin>>v[i];
  //VV<bool> used(h,V<bool>(w,false));
  VV<V<Pi>> c(h,VV<Pi>(w,V<Pi>(4,mp(INF,INF))));

  deque<int> q;
  q.pb(sg);
  q.pb(sr);
  q.pb(0);
  q.pb(0);
  q.pb(0);
  rep(i,0,4)c[sg][sr][i]=mp(0,0);

  while(q.size()){
    int ng,nr,dir,con,cost;
    ng=q.front();q.pop_front();
    nr=q.front();q.pop_front();
    dir=q.front();q.pop_front();
    con=q.front();q.pop_front();
    cost=q.front();q.pop_front();
    //debug(ng,nr,dir,cost);

    int neg,ner;
    rep(i,0,4){
      neg=ng+dx[i],ner=nr+dy[i];

      if(neg<0 || neg>=h || ner<0 || ner>=w)continue;
      //if(used[neg][ner])continue;
      if(v[neg][ner]=='@')continue;


      //used[neg][ner]=true;

      if(1<=con && con<=k-1 && i==dir){
        if(mp(cost,con+1)>=c[neg][ner][i])continue;
        q.push_front(cost);
        q.push_front(con+1);
        q.push_front(i);
        q.push_front(ner);
        q.push_front(neg);
        c[neg][ner][i]=mp(cost,con+1);
    //debug(neg,ner,cost);
         
      }else{
        if(mp(cost+1,con+1)>=c[neg][ner][i])continue;
        q.pb(neg);
        q.pb(ner);
        q.pb(i);
        q.pb(1);
        q.pb(cost+1);
        c[neg][ner][i]=mp(cost+1,con+1);
    //debug(neg,ner,cost);

      }
    }
  }
  
  ll ans=INF;
  rep(i,0,4)chmin(ans,c[gg][gr][i].fs);
  if(ans==INF)cout<<-1<<ENDL;
  else cout<<ans<<ENDL;
}
//! ( . _ . ) ! 
//CHECK overflow,vector_size,what to output?

Measured memory_bytes: 144960