#ifndef ONLINE_JUDGE
#define DEBUG 1
#if DEBUG
#define _GLIBCXX_DEBUG
#endif
#endif
#include <algorithm>
#include <bitset>
#include <cassert>
#include <cmath>
#include <cstring>
#include <deque>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <tuple>
#include <utility>
#include <vector>
using namespace std;
using ll = long long;
using ull = unsigned long long;
using ld = long double;
using vll = vector<ll>;
using vvll = vector<vll>;
using vvvll = vector<vvll>;
using pll = pair<ll, ll>;
using vpll = vector<pll>;
using vvpll = vector<vpll>;
using vvvpll = vector<vvpll>;
using tll = tuple<ll, ll, ll>;
using vtll = vector<tll>;
using vvtll = vector<vtll>;
using vvvtll = vector<vvtll>;
using t4ll = tuple<ll, ll, ll, ll>;
using vt4ll = vector<t4ll>;
using vvt4ll = vector<vt4ll>;
using vvvt4ll = vector<vvt4ll>;
using t5ll = tuple<ll, ll, ll, ll, ll>;
using vt5ll = vector<t5ll>;
using vvt5ll = vector<vt5ll>;
using vvvt5ll = vector<vvt5ll>;
#define all(v) (v).begin(), (v).end()
#define for1(i, n) for (ll i = 0; i < (n); i++)
#define for2(i, m, n) for (ll i = (m); i < (n); i++)
#define for3(i, m, n, d) for (ll i = (m); i < (n); i += (d))
#define rfor2(i, m, n) for (ll i = (m); i > (n); i--)
#define rfor3(i, m, n, d) for (ll i = (m); i > (n); i += (d))
#define PI 3.1415926535897932384626433832795028841971693993751L
#define INF 1111111111111111111LL
#define print(...) print_1(__VA_ARGS__)
#define in(...) in_1(__VA_ARGS__)
#if DEBUG
#define dump(...) dump_1(#__VA_ARGS__, __VA_ARGS__)
#define dumpa(...) dumpa_1(#__VA_ARGS__, __VA_ARGS__)
#else
#define dump(...)
#define dumpa(...)
#endif
template <typename Head>
void dump_1(const char* str, Head&& h)
{
    cerr << str << ": " << h << '\n';
}
template <typename Head, typename... Tail>
void dump_1(const char* str, Head&& h, Tail&&... t)
{
    while (*str != ',') {
        cerr << *str++;
    }
    cerr << ": " << h << ' ';
    dump_1(str + 1, t...);
}
template <typename T>
void dumpa_1(const char* str, const T v[], const ll size)
{
    while (*str != ',') {
        cerr << *str++;
    }
    cerr << ": ";
    for1 (i, size) {
        if (i != 0) {
            cerr << ' ';
        }
        cerr << v[i];
    }
    cerr << '\n';
}
template <typename T1, typename T2>
ostream& operator<<(ostream& os, const pair<T1, T2>& v)
{
    os << v.first << ' ' << v.second;
    return os;
}
template <typename T1, typename T2, typename T3>
ostream& operator<<(ostream& os, const tuple<T1, T2, T3>& v)
{
    os << get<0>(v) << ' ' << get<1>(v) << ' ' << get<2>(v);
    return os;
}
template <typename T>
ostream& operator<<(ostream& os, const vector<T>& v)
{
    for (auto it = v.begin(); it != v.end(); it++) {
        if (it != v.begin()) {
            os << ' ';
        }
        os << *it;
    }
    return os;
}
template <typename T>
ostream& operator<<(ostream& os, const set<T>& v)
{
    for (auto it = v.begin(); it != v.end(); it++) {
        if (it != v.begin()) {
            os << ' ';
        }
        os << *it;
    }
    return os;
}
template <typename T>
ostream& operator<<(ostream& os, const multiset<T>& v)
{
    for (auto it = v.begin(); it != v.end(); it++) {
        if (it != v.begin()) {
            os << ' ';
        }
        os << *it;
    }
    return os;
}
template <typename T1, typename T2>
ostream& operator<<(ostream& os, const map<T1, T2>& v)
{
    os << '{';
    for (auto it = v.begin(); it != v.end(); it++) {
        if (it != v.begin()) {
            os << ", ";
        }
        os << it->first << ':' << it->second;
    }
    os << '}';
    return os;
}
ll divup(ll nume, ll deno)
{
    assert(nume >= 0);
    assert(deno > 0);
    return (nume + deno - 1) / deno;
}
void Yes(void) { cout << "Yes\n"; }
void No(void) { cout << "No\n"; }
void YES(void) { cout << "YES\n"; }
void NO(void) { cout << "NO\n"; }
template <typename T>
bool chmax(T& a, const T& b)
{
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}
template <typename T>
bool chmin(T& a, const T& b)
{
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}
template <typename T>
void vin(vector<T>& v)
{
    ll len = v.size();
    for1 (i, len) {
        cin >> v[i];
    }
}
template <typename Head>
void in_1(Head& h)
{
    cin >> h;
}
template <typename Head, typename... Tail>
void in_1(Head& h, Tail&... t)
{
    cin >> h;
    in_1(t...);
}
template <typename Head>
void print_1(Head&& h)
{
    cout << h << '\n';
}
template <typename Head, typename... Tail>
void print_1(Head&& h, Tail&&... t)
{
    cout << h << ' ';
    print_1(t...);
}
//---------------------------------------------------------
const ll mod = 1000000007LL;  // 10**9 + 7
struct mint {
    ll x;  // typedef long long ll;
    mint(ll x = 0) : x((x % mod + mod) % mod) {}
    mint& operator+=(const mint a)
    {
        if ((x += a.x) >= mod) x -= mod;
        return *this;
    }
    mint& operator-=(const mint a)
    {
        if ((x += mod - a.x) >= mod) x -= mod;
        return *this;
    }
    mint& operator*=(const mint a)
    {
        (x *= a.x) %= mod;
        return *this;
    }
    mint operator+(const mint a) const
    {
        mint res(*this);
        return res += a;
    }
    mint operator-(const mint a) const
    {
        mint res(*this);
        return res -= a;
    }
    mint operator*(const mint a) const
    {
        mint res(*this);
        return res *= a;
    }
    mint pow(ll t) const
    {
        if (!t) return 1;
        mint a = pow(t >> 1);
        a *= a;
        if (t & 1) a *= *this;
        return a;
    }

    // for prime mod
    mint inv() const { return pow(mod - 2); }
    mint& operator/=(const mint a) { return (*this) *= a.inv(); }
    mint operator/(const mint a) const
    {
        mint res(*this);
        return res /= a;
    }
    friend ostream& operator<<(ostream& os, const mint& v)
    {
        os << v.x;
        return os;
    }
};
//---------------------------------------------------------
struct mintcomb {
    vector<mint> fact, ifact;
    mintcomb(int n) : fact(n + 1), ifact(n + 1)
    {
        assert(n < mod);
        fact[0] = 1;
        for (int i = 1; i <= n; ++i) {
            fact[i] = fact[i - 1] * i;
        }
        ifact[n] = fact[n].inv();
        for (int i = n; i >= 1; --i) {
            ifact[i - 1] = ifact[i] * i;
        }
    }
    mint permutation(int n, int k)
    {
        if (k < 0 || k > n) return 0;
        return fact[n] * ifact[n - k];
    }
    mint combination(int n, int k)
    {
        if (k < 0 || k > n) return 0;
        return fact[n] * ifact[k] * ifact[n - k];
    }
};
//---------------------------------------------------------
void solve()
{
    ll H, W, K, y1, x1, y2, x2;
    in(H, W, K, y1, x1, y2, x2);
    x1--;
    y1--;
    x2--;
    y2--;
    vector<string> grid(H);
    for1 (i, H) {
        in(grid[i]);
    }
    const ll dx[] = {-1, 1, 0, 0};
    const ll dy[] = {0, 0, -1, 1};
    // [y][x][方向] かいた数,進んだ数
    vvvpll dist(H, vvpll(W, vpll(4, {INF, INF})));
    // かいた数,進んだ数,y,x,方向
    priority_queue<t5ll, vector<t5ll>, greater<t5ll>> q;
    for1 (d, 4) {
        q.push({1, 0, y1, x1, d});
    }
    while (!q.empty()) {
        auto [c1, c2, y, x, d] = q.top();
        q.pop();
        pll c12 = {c1, c2};
        if (dist[y][x][d] <= c12) continue;
        dist[y][x][d] = c12;
        dump("pop", c1, c2, y, x, d);
        // dump(y, x, dis[y][x]);
        if (y == y2 && x == x2) {
            print(c1);
            return;
        }

        pll c3 = {c12.first + 1, 0};
        for1 (nd, 4) {
            if (nd == d) continue;
            ll nx = x;
            ll ny = y;
            if (dist[ny][nx][nd] <= c3) continue;
            dump("push1", c3.first, c3.second, ny, nx, nd);
            q.push({c3.first, c3.second, ny, nx, nd});
        }

        c12.second++;
        if (c12.second > K) {
            c12.first++;
            c12.second = 1;
        }
        do {
            ll nx = x + dx[d];
            ll ny = y + dy[d];
            if (nx < 0 || ny < 0 || nx >= W || ny >= H) break;
            if (grid[ny][nx] == '@') break;
            if (dist[ny][nx][d] <= c12) break;
            dump("push2", c12.first, c12.second, ny, nx, d);
            q.push({c12.first, c12.second, ny, nx, d});
        } while (false);
    }
    print(-1);
}
//---------------------------------------------------------
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << fixed << setprecision(16);
    cerr << fixed << setprecision(16);
    solve();
}


Measured memory_bytes: 207188