#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#include <numeric>
#include <utility>
#include <tuple>

#define REP(i, a, b) for (int i = int(a); i < int(b); i++)
using namespace std;
using ll = long long int;
using P = pair<ll, ll>;

// clang-format off
#ifdef _DEBUG_
#define dump(...) do{ cerr << __LINE__ << ":\t" << #__VA_ARGS__ << " = "; PPPPP(__VA_ARGS__); cerr << endl; } while(false)
template<typename T> void PPPPP(T t) { cerr << t; }
template<typename T, typename... S> void PPPPP(T t, S... s) { cerr << t << ", "; PPPPP(s...); }
#else
#define dump(...) do{ } while(false)
#endif
template<typename T> vector<T> make_v(size_t a, T b) { return vector<T>(a, b); }
template<typename... Ts> auto make_v(size_t a, Ts... ts) { return vector<decltype(make_v(ts...))>(a, make_v(ts...)); }
template<typename T> bool chmin(T &a, T b) { if (a > b) {a = b; return true; } return false; }
template<typename T> bool chmax(T &a, T b) { if (a < b) {a = b; return true; } return false; }
template<typename T> void print(T a) { cout << a << endl; }
template<typename T, typename... Ts> void print(T a, Ts... ts) { cout << a << ' '; print(ts...); }
template<typename T> istream &operator,(istream &in, T &t) { return in >> t; }
// clang-format on

#include <array>
template<size_t N>
class INDEX {
    array<size_t, N> arr;

public:
    template<typename... T>
    INDEX(T... _arr)
        : arr({{static_cast<size_t>(_arr)...}}) {}
    template<typename... T>
    size_t operator()(T... _arr) {
        size_t position[] = {static_cast<size_t>(_arr)...};
        static_assert(N == size(position));
        size_t res = 0, width = 1;
        for (int i = N - 1; i >= 0; i--) {
            res += width * position[i];
            width *= arr[i];
        }
        return res;
    }
};
template<typename... T>
auto Index(T... args) {
    unsigned int arr[] = {static_cast<unsigned int>(args)...};
    constexpr size_t N = size(arr);
    return INDEX<N>(args...);
}
template<typename T, typename... Args>
auto make_v_flat(T init, Args... args) {
    return vector<T>((1 * ... * args), init);
}

#include <queue>
using T = tuple<ll, int, int, int>;  // x, y, direc, cost;

int main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    ll h, w, k;
    cin, h, w, k;

    ll sx, sy, gx, gy;
    cin, sx, sy, gx, gy;

    auto mp = make_v_flat('@', h + 2, w + 2);
    auto MPindex = Index(h + 2, w + 2);

    REP(i, 1, h + 1) {
        REP(j, 1, w + 1) {
            cin, mp[MPindex(i, j)];
        }
    }

    const ll inf = 1LL << 60;
    auto dp = make_v_flat(inf, h + 2, w + 2, 4);
    auto DPindex = Index(h + 2, w + 2, 4);

    priority_queue<T, vector<T>, greater<T>> q;
    REP(i, 0, 4) {
        q.emplace(0LL, sx, sy, i);
        dp[DPindex(sx, sy, i)] = 0;
    }

    const ll diff[] = {0, 1, 0, -1, 0};

    while (q.size()) {
        auto [cost,x, y, direc] = q.top();
        q.pop();
        if (dp[DPindex(x, y, direc)] < cost) continue;
        dp[DPindex(x, y, direc)] = cost;
        REP(t, 0, 4) {
            ll nx = x + diff[t];
            ll ny = y + diff[t + 1];
            if (mp[MPindex(nx, ny)] == '@') continue;

            ll ncost = cost + 1;
            if (direc != t) {
                ncost = (cost + k - 1) / k * k + 1;
            }

            if (chmin(dp[DPindex(nx, ny, t)], ncost)) {
                q.emplace(ncost,nx, ny, t);
            }
        }
    }

    ll ans = inf;
    REP(i, 0, 4) {
        chmin(ans, dp[DPindex(gx, gy, i)]);
    }

    if (ans == inf) {
        ans = -1;
    } else {
        ans = (ans + k - 1) / k;
    }
    print(ans);
    return 0;
}


Measured memory_bytes: 99828