#define _CRT_SECURE_NO_WARNINGS
#define REL

#pragma GCC target ("avx2")
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")

#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <deque>
#include <queue>
#include <iomanip>
#include <cstdio>
#include <unordered_map>
#include <unordered_set>
#include <map>
#include <string>
#include <set>
#include <bitset>
#include <cstdint>
#include <cstring>
#include <cassert>
#include <complex>
#include <stack> 
#include <random>

using namespace std;

typedef int64_t i64;
typedef long long LL;
typedef long long ll;
typedef long double LD;
typedef complex <LD> cld;
typedef unsigned int uint;
typedef complex <double> cd;
typedef unsigned long long ULL;

#define endl "\n"
#define dendl "\n\n"
#define mp make_pair
#define mt make_tuple
#define size(v) (int)v.size()
#define all(v) v.begin(), v.end()
#define rall(v) v.rbegin(), v.rend()

/////////////////////////////////////////////////////////////////////

template <typename T>
T sqr(T a) {
	return a * a;
}

template <typename T>
int sign(T a) {
	if (a == 0)
		return 0;
	return (a > 0 ? 1 : -1);
}

template <typename T>
bool uax(T& a, const T b) {
	if (a < b) {
		a = b;
		return true;
	}
	return false;
}

template <typename T>
bool uin(T& a, const T b) {
	if (a > b) {
		a = b;
		return true;
	}
	return false;
}

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

template <typename T1, typename T2>
ostream& operator << (ostream& out, pair<T1, T2>& p) {
	out << p.first << ' ' << p.second;
	return out;
}

mt19937_64 rnd(0);

const int LOG = 64;
const int N = (int)2e5 + 7;
const int MAXN = (int)1e6 + 7;
const int MOD = (int)1e9 + 7;
const int INF = (int)2e9 + 7;
const int CONST = 450;
const LL LINF = (i64)1e18;
const LD PI = 3.1415926535897932384626433832795;
const LD EPS = 1;

/////////////////////////////////////////////////////////////////////

struct Kek {
	int x, y, dir, dst, spent;
	Kek() {};
	Kek(int x, int y, int dir, int dst, int spent) :
		x(x), y(y), dir(dir), dst(dst), spent(spent) {};
};

bool operator < (const Kek& a, const Kek& b) {
	if (a.dst == b.dst && a.spent == b.spent)
		return mp(mp(a.x, a.y), a.dir) < mp(mp(b.x, b.y), b.dir);
	return mp(a.dst, a.spent) < mp(b.dst, b.spent);
}

int n, m, k;
int stx, sty, fnx, fny;
vector <vector<char>> f;
vector <vector<vector<pair<int, int>>>> dist;
int v[4] = { -1, 0, 0, 1 }, h[4] = { 0, -1, 1, 0 };

void solve() {
	cin >> n >> m >> k >> stx >> sty >> fnx >> fny;
	f.resize(n + 2, vector<char>(m + 2, '@'));
	for (int i = 1; i <= n; i++) {
		for (int j = 1; j <= m; j++)
			cin >> f[i][j];
	}
	dist.resize(n + 2, vector<vector<pair<int, int>>>(m + 2, vector<pair<int, int>>(4, mp(INF, INF))));
	set <Kek> q;
	for (int i = 0; i < 4; i++) {
		dist[stx][sty][i] = mp(1, 0);
		q.insert(Kek(stx, sty, i, 1, 0));
	}
	while (!q.empty()) {
		auto cur = *q.begin();
		q.erase(*q.begin());
		int x = cur.x, y = cur.y, dir = cur.dir, dst = cur.dst, spent = cur.spent;
		for (int i = 0; i < 4; i++) {
			int nx = x + v[i], ny = y + h[i];
			if (f[nx][ny] == '@')
				continue;
			pair <int, int> cost;
			if (i == dir && spent < k)
				cost = mp(dst, spent + 1);
			else
				cost = mp(dst + 1, 1);
			auto& rel = dist[nx][ny][i];
			if (dist[nx][ny][i] > cost) {
				q.erase(Kek(nx, ny, i, rel.first, rel.second));
				dist[nx][ny][i] = cost;
				q.insert(Kek(nx, ny, i, rel.first, rel.second));
			}
		}
	}
	int ans = INF;
	for (int i = 0; i < 4; i++)
		uin(ans, dist[fnx][fny][i].first);
	cout << (ans == INF ? -1 : ans);
}

int main() {
	double start = clock();
#ifdef _DEBUG
	freopen("input.txt", "r", stdin);
	freopen("output.txt", "w", stdout);
	cout << fixed << setprecision(20);
	cerr << fixed << setprecision(20);
#else
	cout << fixed << setprecision(20);
	ios_base::sync_with_stdio(0);
	cin.tie(0); cout.tie(0);
	rnd.seed(time(0));
#endif

	int t = 1;
	for (int i = 0; i < t; i++) {
		solve();
	}
	
#ifdef _DEBUG
	cout << endl << "Time is " << (clock() - start) / 1000.0;
#endif
}

Measured memory_bytes: 287480