#include <bits/stdc++.h>
using namespace std;

// template {{{
#define  range(i, l, r) for (int i = (int)(l); i < (int)(r); (i) += 1)
#define rrange(i, l, r) for (int i = (int)(r) - 1; i >= (int)(l); (i) -= 1)

#define  whole(f, x, ...) ([&](decltype((x)) container) { return (f)(  begin(container),  end(container), ## __VA_ARGS__); })(x)
#define rwhole(f, x, ...) ([&](decltype((x)) container) { return (f)( rbegin(container), rend(container), ## __VA_ARGS__); })(x)

#define debug(x) cerr << "(" << __LINE__ << ")" << #x << ": " << (x) << endl

using i32 = int;
using u32 = unsigned int;
using i64 = long long;
using u64 = unsigned long long;

// constexpr i32 mod   = 998244353;
constexpr i32 mod   = 1e9 + 7;
constexpr i32 inf   = 1001001001;
constexpr i64 infll = 1001001001001001001ll;

constexpr int dx[] = {0, -1, 1, 0, -1, 1, -1, 1};
constexpr int dy[] = {-1, 0, 0, 1, -1, -1, 1, 1};

struct IoSetup { IoSetup(int x = 15){ cin.tie(0); ios::sync_with_stdio(0); cout << fixed << setprecision(x); cerr << fixed << setprecision(x); } } iosetup;

template <typename T = i64> T input() { T x; cin >> x; return x; }

template <typename T> ostream &operator<<(ostream &os, vector<T> &v) { range(i, 0, v.size()) { os << v[i] << (i + 1 != v.size() ? " " : ""); } return os; }
template <typename T> istream &operator>>(istream &is, vector<T> &v) { for (T &in : v) is >> in; return is; }

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

template <typename T> vector<T> make_vector(size_t a, T b) { return vector<T>(a, b); }
template <typename... Ts> auto make_vector(size_t a, Ts... ts) { return vector<decltype(make_vector(ts...))>(a, make_vector(ts...)); }

template <typename T1, typename T2> inline bool chmax(T1 &a, T2 b) { return a < b && (a = b, true); }
template <typename T1, typename T2> inline bool chmin(T1 &a, T2 b) { return a > b && (a = b, true); }
// }}}

void solver() {
    int h, w, k;
    cin >> h >> w >> k;

    int sy = input() - 1, sx = input() - 1, gy = input() - 1, gx = input() - 1;

    vector< string > cs(h);
    for (auto &c: cs) cin >> c;

    auto dp = make_vector(h, w, inf);
    dp[sy][sx] = 0;

    queue< pair< int, int > > que;
    que.emplace(sy, sx);
    auto used = make_vector(h, w, 2, false);

    while (!que.empty()) {
        auto p = que.front();
        que.pop();

        int x, y;
        tie(y, x) = p;

        range(d, 0, 4) {
            range(t, 1, k + 1) {
                int nx = x + dx[d] * t;
                int ny = y + dy[d] * t;
                if (nx < 0 || w <= nx || ny < 0 || h <= ny) {
                    break;
                }

                if (cs[ny][nx] == '@') break;

                if (dp[y][x] >= dp[ny][nx]) {
                    int cnd;
                    if (d == 0 || d == 3) cnd = 0;
                    else cnd = 1;

                    if (used[ny][nx][cnd]) break;
                    used[ny][nx][cnd] = true;
                    continue;
                }

                if (dp[ny][nx] > dp[y][x] + 1) {
                    dp[ny][nx] = dp[y][x] + 1;
                    que.emplace(ny, nx);
                }
            }
        }
    }

    if (dp[gy][gx] == inf) {
        cout << -1 << endl;
    } else {
        cout << dp[gy][gx] << endl;
    }
}

signed main(int argc, char *argv[]) {
    solver();
}


Measured memory_bytes: 148760