#include <bits/stdc++.h>
#define int long long
#define ll long long
using ull = unsigned long long;
using namespace std;
#define dump(x)                             \
    if (dbg) {                              \
        cerr << #x << " = " << (x) << endl; \
    }
#define overload4(_1, _2, _3, _4, name, ...) name
#define FOR1(n) for (ll i = 0; i < (n); ++i)
#define FOR2(i, n) for (ll i = 0; i < (n); ++i)
#define FOR3(i, a, b) for (ll i = (a); i < (b); ++i)
#define FOR4(i, a, b, c) for (ll i = (a); i < (b); i += (c))
#define FOR(...) overload4(__VA_ARGS__, FOR4, FOR3, FOR2, FOR1)(__VA_ARGS__)
#define FORR(i, a, b) for (int i = (a); i <= (b); ++i)
#define bit(n, k) ((n >> k) & 1) /*nのk bit目*/
namespace mydef {
const int INF = 1ll << 60;
const int MOD = 1e9 + 7;
template <class T>
bool chmin(T& a, const T& b) {
    if (a > b) {
        a = b;
        return 1;
    } else
        return 0;
}
template <class T>
bool chmax(T& a, const T& b) {
    if (a < b) {
        a = b;
        return 1;
    } else
        return 0;
}
void Yes(bool flag = true) {
    if (flag)
        cout << "Yes" << endl;
    else
        cout << "No" << endl;
}
void No(bool flag = true) {
    Yes(!flag);
}
void YES(bool flag = true) {
    if (flag)
        cout << "YES" << endl;
    else
        cout << "NO" << endl;
}
void NO(bool flag = true) {
    YES(!flag);
}
template <typename A, size_t N, typename T>
void Fill(A (&array)[N], const T& val) {
    std::fill((T*)array, (T*)(array + N), val);
}
bool dbg = false;
}  // namespace mydef
using namespace mydef;
#define pb push_back
#define mp make_pair
#define eb emplace_back
#define lb lower_bound
#define ub upper_bound
#define all(v) (v).begin(), (v).end()
#define SZ(x) ((int)(x).size())
#define vi vector<int>
#define vvi vector<vector<int>>
#define vp vector<pair<int, int>>
#define vvp vector<vector<pair<int, int>>>
#define pi pair<int, int>
//#define P pair<int, int>
//#define V vector<int>
//#define S set<int>
#define asn ans

int H, W, K, x[2], y[2];
string c[1010101];
const int dx[] = {1, 0, -1, 0, 1, 1, -1, -1, 0};
const int dy[] = {0, -1, 0, 1, 1, -1, 1, -1, 0};

vector<int> d[1010101];

void solve() {
    for (int i = 0; i < H; i++) {
        d[i].resize(W);
        for (auto& a : d[i])
            a = INF;
    }

    priority_queue<pair<int, pi>, vector<pair<int, pi>>, greater<pair<int, pi>>> que;
    que.push({0, {x[0], y[0]}});

    while (!que.empty()) {
        auto p = que.top();
        que.pop();
        int dist = p.first;
        int x = p.second.first, y = p.second.second;
        if (d[x][y] < dist)
            continue;

        d[x][y] = dist;

        for (int i = 0; i < 4; i++) {
            int nxt_x = x, nxt_y = y;
            for (int j = 0; j < K; j++) {
                nxt_x += dx[i];
                nxt_y += dy[i];
                if (nxt_x < 0 || nxt_x >= H || nxt_y < 0 || nxt_y >= W)
                    break;
                if (c[nxt_x][nxt_y])
                    break;
                if (d[nxt_x][nxt_y] > dist + 1) {
                    d[nxt_x][nxt_y] = dist + 1;
                    que.push({dist + 1, {nxt_x, nxt_y}});
                } else if (d[nxt_x][nxt_y] == dist + 1)
                    continue;
                else
                    break;
            }
        }
    }


    if (d[x[1]][y[1]] == INF)
        d[x[1]][y[1]] = -1;

    cout << d[x[1]][y[1]] << endl;
}

signed main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);


    cin >> H >> W >> K;
    cin >> x[0] >> y[0] >> x[1] >> y[1];
    x[0]--;
    x[1]--;
    y[0]--;
    y[1]--;
    for (int i = 0; i < H; i++) {
        cin >> c[i];
        for (auto& s : c[i]) {
            if (s == '@')
                s = 1;
            else
                s = 0;
        }
    }

    solve();
    return 0;
}


Measured memory_bytes: 70696