#include <algorithm>
#include <bitset>
#include <climits>
#include <cmath>
#include <cstdio>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <unordered_map>
#include <vector>

#define MOD 1000000007
#define MOD2 998244353
#define int long long
#define double long double
#define EPS 1e-9
//#define PI 3.14159265358979

#define rep(i, n) for (int i = 0; i < (int)(n); i++)

using namespace std;

template < typename T >
ostream &operator<<(ostream &os, const vector< T > &A) {
	for (int i = 0; i < A.size(); i++)
		os << A[i] << " ";
	os << endl;
	return os;
}
template <>
ostream &operator<<(ostream &os, const vector< vector< int > > &A) {
	int N = A.size();
	for (int i = 0; i < N; i++) {
		for (int j = 0; j < A[i].size(); j++)
			os << A[i][j] << " ";
		os << endl;
	}
	return os;
}

typedef pair< int, int > pii;
typedef long long ll;

struct edge {
	int from, to, d, c;
	edge(int _from = 0, int _to = 0, int _d = 0, int _c = 0) {
		from = _from;
		to = _to;
		d = _d;
		c = _c;
	}
	bool operator<(const edge &rhs) const {
		return (d == rhs.d) ? (c < rhs.c) : (d < rhs.d);
	}
};
struct aabb {
	int x1, y1, x2, y2;
	aabb(int x1, int y1, int x2, int y2) : x1(x1), y1(y1), x2(x2), y2(y2) {}
};

typedef vector< edge > edges;
typedef vector< edges > graph;
struct flow {
	int to, cap, rev, cost;
	flow(int to = 0, int cap = 0, int rev = 0, int cost = 0) : to(to), cap(cap), rev(rev), cost(cost) {}
};
typedef vector< vector< flow > > flows;

const int di[4] = {0, -1, 0, 1};
const int dj[4] = {-1, 0, 1, 0};
const int ci[5] = {0, 0, -1, 0, 1};
const int cj[5] = {0, -1, 0, 1, 0};
const ll LINF = LLONG_MAX / 2;
const int INF = INT_MAX / 2;
const double PI = acos(-1);

int pow2(int n) { return 1LL << n; }
template < typename T, typename U >
bool chmin(T &x, const U &y) {
	if (x > y) {
		x = y;
		return true;
	}
	return false;
}
template < typename T, typename U >
bool chmax(T &x, const U &y) {
	if (x < y) {
		x = y;
		return true;
	}
	return false;
}

struct initializer {
	initializer() {
		cout << fixed << setprecision(20);
	}
};
initializer _____;
vector< int > dijkstra(graph &G, int s) {
	///stat must have "<"&">"
	///init d=vector<stat>
	vector< int > d(G.size(), LINF);
	d[s] = 0;
	//init q=p-queue<pair<stat,index> >
	priority_queue< pii, vector< pii >, greater< pii > > q;
	q.push(pii(0, s));

	while (!q.empty()) {
		pii p = q.top();
		q.pop();
		if (d[p.second] < p.first)
			continue;
		for (int i = 0; i < G[p.second].size(); i++) {
			edge e = G[p.second][i];
			if (p.first + e.d < d[e.to]) {
				d[e.to] = p.first + e.d;
				q.push(pii(d[e.to], e.to));
			}
		}
	}
	return d;
}
int N, M, K, T, Q, H, W;
signed main() {
	cin >> H >> W >> K;
	int x1, y1, x2, y2;
	cin >> x1 >> y1 >> x2 >> y2;
	--x1;
	--y1;
	--x2;
	--y2;
	vector< string > C(H);
	rep(i, H) cin >> C[i];
	vector< vector< int > > grid(H, vector< int >(W, 0));
	rep(i, H) rep(j, W) if (C[i][j] == '@') grid[i][j] = 1;
	vector< vector< vector< pii > > > d(H, vector< vector< pii > >(W, vector< pii >(4, pii(LINF, LINF))));
	d[x1][y1][0] = pii(0, 0);
	priority_queue< pair< pii, pair< pii, int > >, vector< pair< pii, pair< pii, int > > >, greater< pair< pii, pair< pii, int > > > > q;
	pair< pii, pair< pii, int > > s;
	s.first = pii(0, 0);
	s.second.first = pii(x1, y1);
	s.second.second = 0;
	q.push(s);
	while (!q.empty()) {
		pair< pii, pair< pii, int > > p = q.top();
		q.pop();
		int i = p.second.first.first;
		int j = p.second.first.second;
		int k = p.second.second;
		pii dist = p.first;
		if (d[i][j][k] < dist)
			continue;
		int ni = i + di[k];
		int nj = j + dj[k];
		if (0 <= ni && ni < H && 0 <= nj && nj < W && (!grid[ni][nj])) {
			pii ndist = dist;
			ndist.second++;
			if (ndist.second >= K) {
				ndist.second -= K;
				ndist.first++;
			}
			if (ndist < d[ni][nj][k]) {
				d[ni][nj][k] = ndist;
				q.push(make_pair(ndist, pair< pii, int >(pii(ni, nj), k)));
			}
		}
		int nk = k;
		pii ndist = dist;
		if (ndist.second > 0) {
			ndist.first++;
			ndist.second = 0;
		}
		rep(_, 3) {
			nk = (nk + 1) % 4;
			if (ndist < d[i][j][nk]) {
				d[i][j][nk] = ndist;
				q.push(make_pair(ndist, pair< pii, int >(pii(i, j), nk)));
			}
		}
	}
	pii ans = pii(LINF, LINF);
	rep(k, 4) {
		chmin(ans, d[x2][y2][k]);
	}
	if (ans == pii(LINF, LINF)) {
		cout << -1 << endl;
	} else {
		if (ans.second > 0)
			ans.first++;
		cout << ans.first << endl;
	}
	return 0;
}

Measured memory_bytes: 215096