#ifdef LOCAL
//#define _GLIBCXX_DEBUG
#endif
//#pragma GCC target("avx512f,avx512dq,avx512cd,avx512bw,avx512vl")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef pair<ll, ll> P;
typedef pair<int, int> Pi;
typedef vector<ll> Vec;
typedef vector<int> Vi;
typedef vector<string> Vs;
typedef vector<P> VP;
typedef vector<vector<ll>> VV;
typedef vector<vector<int>> VVi;
typedef vector<vector<vector<ll>>> VVV;
typedef vector<vector<vector<vector<ll>>>> VVVV;

#define REP(i, a, b) for(ll i=(a); i<(b); i++)
#define PER(i, a, b) for(ll i=(a); i>=(b); i--)
#define rep(i, n) REP(i, 0, n)
#define per(i, n) PER(i, n, 0)
const ll INF=1e18+18;
const ll MOD=1000000007;
#define Yes(n) cout << ((n) ? "Yes" : "No") << endl;
#define YES(n) cout << ((n) ? "YES" : "NO") << endl;
#define ALL(v) v.begin(), v.end()
#define rALL(v) v.rbegin(), v.rend()
#define pb(x) push_back(x)
#define mp(a, b) make_pair(a,b)
#define Each(a,b) for(auto &a :b)
#define rEach(i, mp) for (auto i = mp.rbegin(); i != mp.rend(); ++i)
#ifdef LOCAL
#define dbg(x_) cerr << #x_ << ":" << x_ << endl;
#define dbgmap(mp) cerr << #mp << ":"<<endl; for (auto i = mp.begin(); i != mp.end(); ++i) { cerr << i->first <<":"<<i->second << endl;}
#define dbgarr(n,m,arr) rep(i,n){rep(j,m){cerr<<arr[i][j]<<" ";}cerr<<endl;}
#define dbgdp(n,arr) rep(i,n){cerr<<arr[i]<<" ";}cerr<<endl;
#define dbgmint(n,arr) rep(i,n){cerr<<arr[i].x<<" ";}cerr<<endl;
#define dbgarrmint(n,m,arr) rep(i,n){rep(j,m){cerr<<arr[i][j].x<<" ";}cerr<<endl;}
#else
#define dbg(...)
#define dbgmap(...)
#define dbgarr(...)
#define dbgdp(...)
#define dbgmint(...)
#define dbgarrmint(...)
#endif
#define out(a) cout<<a<<endl
#define out2(a,b) cout<<a<<" "<<b<<endl
#define vout(v) rep(i,v.size()){cout<<v[i]<<" ";}cout<<endl
#define Uniq(v) v.erase(unique(v.begin(), v.end()), v.end())
#define fi first
#define se second

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

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

template<typename T>istream& operator>>(istream&i,vector<T>&v)
{rep(j,v.size())i>>v[j];return i;}

// vector
template<typename T>
ostream &operator<<(ostream &s, const vector<T> &v) {
    int len=v.size();
    for(int i=0; i<len; ++i) {
        s<<v[i];
        if(i<len-1) s<<"	";
    }
    return s;
}

// 2 dimentional vector
template<typename T>
ostream &operator<<(ostream &s, const vector<vector<T> > &vv) {
    int len=vv.size();
    for(int i=0; i<len; ++i) {
        s<<vv[i]<<endl;
    }
    return s;
}

void dijkstra(vector<VP> g, ll start, Vec &dist) {
    priority_queue<P, vector<P>, function<bool(P, P)>> q([](P a, P b)->ll {
        return a.second > b.second;
    });
    dist[start] = 0;
    q.push(mp(start, 0));
    while (!q.empty()) {
        P now = q.top();
        q.pop();
        Each(nxt, g[now.fi]) {
            if(chmin(dist[nxt.fi], now.se+nxt.se)) {
                q.push(mp(nxt.fi, dist[nxt.fi]));
            }
        }
    }
}

int solve(){
    ll h,w,k;
    cin>>h>>w>>k;
    ll sy,sx,gy,gx;
    cin>>sy>>sx>>gy>>gx;
    sy--;sx--;gy--;gx--;
    vector<vector<char>> g(h, vector<char>(w));
    rep(i,h){
        rep(j,w){
            cin>>g[i][j];
        }
    }
    //h,w,K
    VVV dist(h,VV(w,Vec(4,INF)));
    VVV process(h,VV(w,Vec(4,INF)));
    auto in = [&](ll y, ll x) {
        return y >= 0 && y < h && x >= 0 && x < w;
    };
    //queue<pair<P,P>> q;
    priority_queue<pair<P,P>, vector<pair<P,P>>, function<bool(pair<P,P>, pair<P,P>)>> q([](pair<P,P> a, pair<P,P> b)->ll {
        return a.se.se > b.se.se;
    });

    Vec dx = {1,0,-1,0,1,-1,1,-1};
    Vec dy = {0,1,0,-1,1,1,-1,-1};
    rep(i,4){
        dist[sy][sx][i]=1;
        process[sy][sx][i]=0;
        q.push(mp(mp(sy,sx),mp(i,1LL)));
    }

    while(!q.empty()){
        pair<P,P> pp = q.top();
        q.pop();
        auto[y,x] = pp.fi;
        auto[pre, pred] = pp.se;
        ll &proc = process[y][x][pre];
        rep(dir,4){
            ll ny = y+dy[dir];
            ll nx = x+dx[dir];
            if(!in(ny,nx))continue;
            if(g[ny][nx]=='@')continue;

            //方向同じ
            if(pre==dir && proc<k){
                if(chmin(dist[ny][nx][dir], pred)){
                    q.emplace(mp(ny,nx),mp(dir,dist[ny][nx][dir]));
                    process[ny][nx][dir] = proc + 1;
                }else if(dist[ny][nx][dir]==pred){
                    if(chmin(process[ny][nx][dir],proc+1)){
                        q.emplace(mp(ny,nx),mp(dir,dist[ny][nx][dir]));
                    }
                }
            }else{
                if(chmin(dist[ny][nx][dir],pred+1)){
                    q.emplace(mp(ny,nx),mp(dir,dist[ny][nx][dir]));
                    process[ny][nx][dir] = 1;
                }else if(dist[ny][nx][dir]==dist[y][x][dir]+1){
                    if(chmin(process[ny][nx][dir],1LL)){
                        q.emplace(mp(ny,nx),mp(dir,dist[ny][nx][dir]));
                    }
                }
            }
        }
    }
    ll ans = INF;
//    rep(i,4){
//        rep(ih,h){
//            rep(iw,w){
//                cerr<<dist[ih][iw][i]<< " ";
//            }
//            cerr<<endl;
//        }
//    }
//    rep(i,4){
//        rep(ih,h){
//            rep(iw,w){
//                cerr<<process[ih][iw][i]<< " ";
//            }
//            cerr<<endl;
//        }
//    }
    rep(i,4){
        chmin(ans,dist[gy][gx][i]);
    }
    if(ans==INF){
        out(-1);
    }else{
        out(ans);
    }
    return  0;
}

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    cout<<std::setprecision(10);
    solve();
}


Measured memory_bytes: 215176