#include <bits/stdc++.h>
#include <unistd.h>
#include <sys/time.h>
#include <stdlib.h>

using namespace std;

typedef long long ll;
typedef pair<ll, ll> P;
typedef pair<P, ll> T;
typedef pair<long double , ll> Ps;
typedef pair<ll, bool> Pb;

const ll INF = 1e18;
const ll fact_table = 3200008;
long double Pi = 3.1415926535897932384626;

priority_queue <ll> pql;
priority_queue <P> pqp;
priority_queue <P> bag;
//big priority queue
priority_queue <ll, vector<ll>, greater<ll> > pqls;
priority_queue <P, vector<P>, greater<P> > pqps;
//small priority queue
//top pop

ll dx[8] = {1, 0, -1, 0, 1, 1, -1, -1};
ll dy[8] = {0, 1, 0, -1, 1, -1, -1, 1};
char dir[] = "DRUL";
//↓,→,↑,←

#define endl "\n"
#ifdef ENJAPMA
#undef endl
#endif
#define p(x) cout<<x<<endl;
#define el cout<<endl;
#define pe(x) cout<<x<<" ";
#define ps(x) cout<<fixed<<setprecision(25)<<x<<endl;
#define pu(x) cout<<(x);
#define pb push_back
#define lb lower_bound
#define ub upper_bound
#define CLEAR(a) a = decltype(a)();
#define pc(x) cout << x << ",";
#define rep(i, n) for (ll i = 0; i < (n); i ++)

// const ll mod = 998244353ll;
const ll mod = 1000000007ll;

ll mypow(ll a, ll b, ll mod) {ll x = 1; while (b) {while (!(b & 1)) {(a *= a) %= mod; b >>= 1;}(x *= a) %= mod; b--;} return x;}
void YES(bool cond) { if (cond) { p("YES");} else { p("NO");} return;}
void Yes(bool cond) { if (cond) { p("Yes");} else { p("No");} return;}

ll line_count = 0;

void line(){

    line_count ++;
    string s = (line_count % 2) ? "v-v-v-v-v-v-v-v-v-v" : "^-^-^-^-^-^-^-^-^-^";
    cout << endl << s << endl << endl;
}

/*
ll fact[fact_table + 5],rfact[fact_table + 5];

void c3_init(){
    fact[0] = rfact[0] = 1;
    for(ll i=1; i<=fact_table; i++){
        fact[i] = (fact[i-1]*i) % mod;
    }
    rfact[fact_table] = mypow(fact[fact_table],mod - 2, mod);
    for(ll i=fact_table; i>=1; i--){
       rfact[i-1] = rfact[i] * i;
       rfact[i-1] %= mod;
    }
    return;}
ll c3(ll n,ll r){
    return (((fact[n] * rfact[r]) % mod ) * rfact[n-r]) % mod;}
*/

bool multicase = false;

ll n, m, k, num, a, b, c, d, e, h, q, ans, sum;
string s;

typedef vector<ll> vec;
typedef vector<vector<ll>> mat;

void solve() {
    ll h, w;
    cin >> h >> w >> k;
    ll sx, sy, gx, gy;
    cin >> sx >> sy >> gx >> gy;
    sx --; sy --; gx --; gy --;
    mat dp(h, vec(w, 0));
    for(int i=0;i<h;i++){
        string s;
        cin >> s;
        for(int j=0;j<w;j++){
            if(s[j] == '@')dp[i][j] = 1;
        }
    }
    mat cost(h, vec(w, INF));
    queue<P> q;
    q.push(P(sx, sy));
    cost[sx][sy] = 0;

    while(q.size()){
        P v = q.front(); q.pop();

        if (v.first == gx && v.second == gy) break;

        for (int i=0;i<4;i++){
            int nx = v.first, ny = v.second;
            for (int j=1;j<=k;j++){
                nx += dx[i], ny += dy[i];
                if (nx < 0 || h <= nx || ny < 0 || w <= ny) break;
                if (dp[nx][ny] == 1) break;
                if (cost[nx][ny] == cost[v.first][v.second]) break;
                if (cost[nx][ny] != INF) continue;

                q.push(P(nx, ny));
                cost[nx][ny] = cost[v.first][v.second] + 1;
            }
        }
    }

    ll ans = cost[gx][gy];

    if (ans == INF) {
        p(-1);
    } else {
        p(ans);
    }


    return;
}

int main() {
    // init();
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    ll q, testcase = 1;
    if (multicase) {
        cin >> q;
    } else {
        q = 1;
    }
    while (q--) {
        // pu("Case ");pu("#");pu(testcase);pu(": ");
        solve();
        testcase++;
    }
    // solve();
    return 0;
}
















Measured memory_bytes: 26764