//header
#ifdef LOCAL
    #include "/Users/takakurashokichi/Desktop/atcoder/cxx-prettyprint-master/prettyprint.hpp"
    #define debug(x) cout << x << endl
#else
    #define debug(...) 42
#endif
    #pragma GCC optimize("Ofast")
    #include <bits/stdc++.h>
    //types
    using namespace std;
    using ll = long long;
    using ul = unsigned long long;
    using ld = long double;
    typedef pair < ll , ll > Pl;        
    typedef pair < int, int > Pi;
    typedef vector<ll> vl;
    typedef vector<int> vi;
    template< typename T >
    using mat = vector< vector< T > >;
    template< int mod >
    struct modint {
        int x;

        modint() : x(0) {}

        modint(int64_t y) : x(y >= 0 ? y % mod : (mod - (-y) % mod) % mod) {}

        modint &operator+=(const modint &p) {
            if((x += p.x) >= mod) x -= mod;
            return *this;
        }

        modint &operator-=(const modint &p) {
            if((x += mod - p.x) >= mod) x -= mod;
            return *this;
        }

        modint &operator*=(const modint &p) {
            x = (int) (1LL * x * p.x % mod);
            return *this;
        }

        modint &operator/=(const modint &p) {
            *this *= p.inverse();
            return *this;
        }

        modint operator-() const { return modint(-x); }

        modint operator+(const modint &p) const { return modint(*this) += p; }

        modint operator-(const modint &p) const { return modint(*this) -= p; }

        modint operator*(const modint &p) const { return modint(*this) *= p; }

        modint operator/(const modint &p) const { return modint(*this) /= p; }

        bool operator==(const modint &p) const { return x == p.x; }

        bool operator!=(const modint &p) const { return x != p.x; }

        modint inverse() const {
            int a = x, b = mod, u = 1, v = 0, t;
            while(b > 0) {
            t = a / b;
            swap(a -= t * b, b);
            swap(u -= t * v, v);
            }
            return modint(u);
        }

        modint pow(int64_t n) const {
            modint ret(1), mul(x);
            while(n > 0) {
            if(n & 1) ret *= mul;
            mul *= mul;
            n >>= 1;
            }
            return ret;
        }

        friend ostream &operator<<(ostream &os, const modint &p) {
            return os << p.x;
        }

        friend istream &operator>>(istream &is, modint &a) {
            int64_t t;
            is >> t;
            a = modint< mod >(t);
            return (is);
        }

        static int get_mod() { return mod; }
    };
    //abreviations
    #define all(x) (x).begin(), (x).end()
    #define rall(x) (x).rbegin(), (x).rend()
    #define rep_(i, a_, b_, a, b, ...) for (int i = (a), max_i = (b); i < max_i; i++)
    #define rep(i, ...) rep_(i, __VA_ARGS__, __VA_ARGS__, 0, __VA_ARGS__)
    #define rrep_(i, a_, b_, a, b, ...) for (int i = (b-1), min_i = (a); i >= min_i; i--)
    #define rrep(i, ...) rrep_(i, __VA_ARGS__, __VA_ARGS__, 0, __VA_ARGS__)
    #define SZ(x) ((int)(x).size())
    #define pb(x) push_back(x)
    #define eb(x) emplace_back(x)
    #define mp make_pair
    #define print(x) cout << x << endl
    #define vsum(x) accumulate(x, 0LL)
    #define vmax(a) *max_element(all(a))
    #define vmin(a) *min_element(all(a))
    #define lb(c, x) distance((c).begin(), lower_bound(all(c), (x)))
    #define ub(c, x) distance((c).begin(), upper_bound(all(c), (x)))
    //functions
    ll gcd(ll a, ll b) { return b ? gcd(b, a%b) : a; }
    ll lcm(ll a, ll b) { return a/gcd(a, b)*b;}
    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; }
    template< typename T >
    T mypow(T x, ll n) {
        T ret = 1;
        while(n > 0) {
            if(n & 1) (ret *= x);
            (x *= x);
            n >>= 1;
        }
        return ret;
    }
    ll modpow(ll x, ll n, const ll mod) {
        ll ret = 1;
        while(n > 0) {
            if(n & 1) (ret *= x);
            (x *= x);
            n >>= 1;
            x%=mod;
            ret%=mod;
        }
        return ret;
    }
    uint64_t my_rand(void) {
        static uint64_t x = 88172645463325252ULL;
        x = x ^ (x << 13); x = x ^ (x >> 7);
        return x = x ^ (x << 17);
    }
    //graph template
    template< typename T >
    struct edge {
        int src, to;
        T cost;

        edge(int to, T cost) : src(-1), to(to), cost(cost) {}

        edge(int src, int to, T cost) : src(src), to(to), cost(cost) {}

        edge &operator=(const int &x) {
            to = x;
            return *this;
        }
        operator int() const { return to; }
    };
    template< typename T >
    using Edges = vector< edge< T > >;
    template< typename T >
    using WeightedGraph = vector< Edges< T > >;
    using UnWeightedGraph = vector< vector< int > >;

//constant
//#define inf 1000000005LL
#define inf 4000000000000000005LL
#define mod 1000000007LL
#define endl '\n'
typedef modint<mod> mint;
const long double eps = 0.0001;
const long double PI  = 3.141592653589793;
//library
int k;
vi go(int x, int y, deque<int>& que, vector<set<int>>& tate, vector<set<int>>& yoko,int h, int w, mat<char>& ike){
    auto now = yoko[x].upper_bound(y);
    vector<int> kesu;
    while(now!=yoko[x].end()&&(*now)<=y+k){
        //debug(*now);
        if(ike[x][*now]=='@')break;
        kesu.pb(*now);
        now++;
    }
    now = yoko[x].lower_bound(y);
    while(*now){
        if(now==yoko[x].begin())break;
        now--;
        if(*now+k<y)break;
        if(ike[x][*now]=='@')break;
        kesu.pb(*now);
    }
    return kesu;
}
int main(){
    cin.tie(0);
    ios::sync_with_stdio(0);
    cout << setprecision(20);
    int h, w;cin>>h>>w>>k;
    int a, b, c, d; cin>>a>>b>>c>>d;
    a--;b--;c--;d--;
    mat<char> ike(h, vector<char>(w)), iket(w, vector<char>(h));
    rep(i, h)rep(j, w)cin>>ike[i][j], iket[j][i] = ike[i][j];
    mat<int> dist(h, vi(w, -1));
    dist[a][b] = 0;
    deque<int> que;
    que.pb(a*w+b);
    vector<set<int>> tate(w), yoko(h);
    rep(i, h)rep(j, w){
        tate[j].insert(i);
        yoko[i].insert(j);
    }
    yoko[a].erase(b);
    tate[b].erase(a);
    while(que.size()){
        int v = que.front();
        que.pop_front();
        int x = v/w, y = v%w;
        vi kesu = go(x, y, que, tate, yoko, h, w, ike);
        for(int ny:kesu){
            que.pb(x*w+ny);
            dist[x][ny]=dist[x][y]+1;
            yoko[x].erase(ny);
            tate[ny].erase(x);
        }
        kesu = go(y, x, que, yoko, tate, w, h, iket);
        for(int nx:kesu){
            que.pb(nx*w+y);
            dist[nx][y]=dist[x][y]+1;
            tate[y].erase(nx);
            yoko[nx].erase(y);
        }
    }
    print(dist[c][d]);
    //debug(dist);
}

Measured memory_bytes: 203392