#include <bits/stdc++.h>
using namespace std;
using LL = long long;
using LD = long double;
using PII = pair<int, int>;
using PLI = pair<long long, int>;
using PLL = pair<long long, long long>;
using TI = tuple<int, int, int>;
mt19937 mrand(random_device{}());
int rnd(int x) { return mrand() % x; }
template<class A, class B> ostream& operator <<(ostream& out, const pair<A, B> &p) {
    return out << "(" << p.first << ", " << p.second << ")";
}
template <typename T, size_t N>
ostream& operator <<(ostream& out, const array<T, N>& a) {
  out << "["; bool first = true;
  for (auto& v : a) { out << (first ? "" : ", "); out << v; first = 0;} out << "]";
  return out;
}
template <typename T>
ostream& operator <<(ostream& out, const vector<T>& a) {
  out << "["; bool first = true;
  for (auto& v : a) { out << (first ? "" : ", "); out << v; first = 0;} out << "]";
  return out;
}
template <typename T>
ostream& operator <<(ostream& out, const deque<T>& a) {
  out << "["; bool first = true;
  for (auto& v : a) { out << (first ? "" : ", "); out << v; first = 0;} out << "]";
  return out;
}
template <typename T, class Cmp>
ostream& operator <<(ostream& out, const set<T, Cmp>& a) {
  out << "{"; bool first = true;
  for (auto& v : a) { out << (first ? "" : ", "); out << v; first = 0;} out << "}";
  return out;
}
template <typename U, typename T, class Cmp>
ostream& operator <<(ostream& out, const map<U, T, Cmp>& a) {
  out << "{"; bool first = true;
  for (auto& p : a) { out << (first ? "" : ", "); out << p.first << ":" << p.second; first = 0;} out << "}";
  return out;
}
template<class T> inline void YES(T condition) { 
    if(condition) cout << "YES" << endl;
    else cout << "NO" << endl;
}
template<class T> inline void Yes(T condition) {
    if(condition) cout << "Yes" << endl;
    else cout << "No" << endl;
}
template<class T> T gcd(T a, T b) {
    while (b) {
        T tmp = b;
        b = a % b;
        a = tmp;
    }
    return a;
}
template<class T> T lcm(T a, T b){
    return a / gcd(a, b) * b;
}

#define trace(...) __f(#__VA_ARGS__, __VA_ARGS__)
template <typename Arg1>
void __f(const char* name, Arg1&& arg1){
  cerr << name << ": " << arg1 << endl;
}
template <typename Arg1, typename... Args>
void __f(const char* names, Arg1&& arg1, Args&&... args){
  const char* comma = strchr(names + 1, ',');
  cerr.write(names, comma - names) << ": " << arg1 << " |";
  __f(comma + 1, args...);
}

long long qpow(long long a, long long b, int MOD) {
    if (b == 0) return 1;
    long long res = 1;
    while (b) {
        if (b & 1) res = (res * a) % MOD;
        a = (a * a) % MOD;
        b >>= 1;
    }
    return res;
}

const int MOD = 1e9 + 7;
const int maxn = 2e6;
const int INF = 1 << 30;
int fac[maxn + 5];
int invfac[maxn + 5];
void init() {
    fac[0] = 1;
    for (int i = 1; i <= maxn; i++) fac[i] = 1LL * fac[i - 1] * i % MOD;
    invfac[maxn] = (int)(qpow(fac[maxn], MOD - 2, MOD));
    for (int i = maxn - 1; i >= 0; i--) invfac[i] = 1LL * invfac[i + 1] * (i + 1) % MOD;
}
int C(int n, int k) {
    assert(0 <= k && n >= k);
    int tmp = (int)(1LL * invfac[k] * invfac[n - k] % MOD);
    return (int)(1LL * fac[n] * tmp % MOD);
}

// struct Node {
//     int x, y, pdi, step, pd;
// };
// bool operator>(Node& a, Node& b) {
//     return a.pd < b.pd;
// }
struct Node {
    int x, y, pdi, step, pd;

    Node(int xx, int yy, int pdii, int stepp, int pdd) {
        x = xx; y = yy; pdi = pdii; step = stepp; pd = pdd;
    }

    bool operator<(const Node& other) const {
        return pd > other.pd;
    }
};


int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};
int main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);

    int n, m, k;
    cin >> n >> m >> k;
    int x1, y1, x2, y2;
    cin >> x1 >> y1 >> x2 >> y2;
    x1--; y1--; x2--; y2--;
    vector<string> mat(n);
    for (int i = 0; i < n; i++) {
        cin >> mat[i];
    }

    vector<vector<int>> d(n, vector<int>(m, INF));
    d[x1][y1] = 0;
    queue<PII> q;
    q.emplace(x1, y1);
    while (!q.empty()) {
        PII p = q.front(); q.pop();
        int x = p.first, y = p.second;
        for (int di = 0; di < 4; di++) {
            int ncost = d[x][y] + 1;
            for (int i = 1; i <= k; i++) {
                int nx = x + dx[di] * i, ny = y + dy[di] * i;
                if (nx < 0 || nx >= n || ny < 0 || ny >= m) break;
                if (mat[nx][ny] == '@') break;
                if (d[nx][ny] > ncost) {
                    d[nx][ny] = ncost;
                    q.emplace(nx, ny);
                } else if (d[nx][ny] == ncost) continue;
                else break;
            }
        }
    }

    // trace(d);
    cout << (d[x2][y2] == INF ? -1 : d[x2][y2]) << '\n';

    // Dijkstra
    // vector<vector<vector<int>>> d(n, vector<vector<int>>(m, vector<int>(4, INF)));
    // vector<vector<vector<int>>> vis(n, vector<vector<int>>(m, vector<int>(4, 0)));
    // priority_queue<Node> q;
    // for (int di = 0; di < 4; di++) {
    //     vis[x1][y1][di] = 1;
    //     int nx = x1 + dx[di], ny = y1 + dy[di];
    //     if (nx < 0 || nx >= n || ny < 0 || ny >= m) continue;
    //     if (mat[nx][ny] == '@') continue;
    //     Node tmp(nx, ny, di, 1, 1);
    //     q.push(tmp);
    //     vis[nx][ny][di] = 1;
    //     d[nx][ny][di] = 1;
    // }

    // bool ok = false;
    // int ans = INF;
    // while (!q.empty()) {
    //     Node tmp = q.top(); q.pop();
    //     int x = tmp.x, y = tmp.y, pdi = tmp.pdi, step = tmp.step, pd = tmp.pd;
    //     // trace(x, y, pdi, step, pd);
    //     if (pd >= ans) break;
    //     for (int di = 0; di < 4; di++) {
    //         int nx = x + dx[di], ny = y + dy[di];
    //         if (nx < 0 || nx >= n || ny < 0 || ny >= m) continue;
    //         if (mat[nx][ny] == '@') continue;
    //         if (vis[nx][ny][di]) continue;
    //         vis[nx][ny][di] = 1;
    //         int add = (step == k ? 1 : (pdi == di ? 0 : 1));
    //         int nd = pd + add;
    //         if (nx == x2 && ny == y2 && ans > nd) {
    //             ok = true;
    //             ans = nd;
    //             continue;
    //         }
    //         Node tmp2(nx, ny, di, (step == k ? 1 : (pdi == di ? step + 1 : 1)), nd);
    //         q.push(tmp2);
    //     }
    // }

    // if (!ok) {cout << -1 << '\n';}
    // else cout << ans << '\n';


    // deque<pair<PII, PII>> q;
    
    // vector<vector<vector<int>>> d(n, vector<vector<int>>(m, vector<int>(4, INF)));
    // for (int di = 0; di < 4; di++) d[x1][y1][di] = 0;
    // for (int di = 0; di < 4; di++) {
    //     int nx1 = x1 + dx[di], ny1 = y1 + dy[di];
    //     if (nx1 < 0 || nx1 >= n || ny1 < 0 || ny1 >= m) continue;
    //     if (mat[nx1][ny1] == '@') continue;
    //     q.emplace_back(make_pair(nx1, ny1), make_pair(di, 1));
    //     d[nx1][ny1][di] = 1;
    // }

    // while (!q.empty()) {
    //     auto p = q.front(); q.pop_front();
    //     PII xy = p.first, did = p.second;
    //     int x = xy.first, y = xy.second, pdi = did.first, pd = did.second;
    //     for (int di = 0; di < 4; di++) {
    //         int nx = x + dx[di], ny = y + dy[di];
    //         if (nx < 0 || nx >= n || ny < 0 || ny >= m) continue;
    //         if (mat[nx][ny] == '@') continue;
    //         int pred = d[x][y][pdi];
    //         int add = (pd == k) ? 1 : ((pdi == di) ? 0 : 1);
    //         if (d[nx][ny][di] > pred + add) {
    //             d[nx][ny][di] = pred + add;
    //             q.emplace_back(make_pair(nx, ny), make_pair(di, (pd == k) ? 1 : (pdi == di ? pd + 1 : 1)));
    //         }
    //     }
    // }

    // // trace(d);
    // int ans = INF;
    // for (int di = 0; di < 4; di++) ans = min(ans, d[x2][y2][di]);
    // cout << (ans == INF ? -1 : ans) << '\n';



    return 0;
}


Measured memory_bytes: 12160