#include <iostream>
#include <string>
#include <vector>
#include <set>
#include <stack>
#include <queue>
#include <map>
#include <algorithm>
#include <iomanip>
#include <math.h>
#include <string.h>
#include <cstdio>
#include <tuple>
#include <numeric>
using namespace std; using ll = long long; using ld = long double;  using pll = pair<ll, ll>;
using vl = vector<ll>; using vll = vector<vl>; using vpll = vector<pll>;
using vs = vector<string>; using tll = tuple<ll, ll, ll>; using vtll = vector<tll>;
const ld PI = 3.1415926535897932;
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#define mp make_pair
#define mt make_tuple
#define pb push_back
#define co(i) cout << i << endl;
#define co2(i,j) cout << i << " " << j << endl;
#define co3(i) cout << i << " ";
#define po(i) cout << i.first << " " << i.second << endl;
void in() {}
void debug_out() { cerr << endl; }
template<typename Head, typename... Tail>
void debug_out(Head h, Tail... t) {
	cerr << " " << h;
	if (sizeof...(t) > 0) cerr << " :";
	debug_out(t...);
}
template <typename T>
ostream& operator<<(ostream& os, vector<T> vec) {
	for (size_t i = 0; i < vec.size(); i++)os << vec[i] << (i + 1 == vec.size() ? "" : " ");
	return os;
}
ll ctoi(char c) {
	switch (c) {
	case '0': return 0; case '1': return 1; case '2': return 2;
	case '3': return 3; case '4': return 4; case '5': return 5;
	case '6': return 6; case '7': return 7; case '8': return 8;
	case '9': return 9;  default: return 0;
	}
}
bool pairCompare(const pll firstElof, pll secondElof)
{
	return firstElof.first > secondElof.first;
}
//**Snippetリスト**//
//rep, vin, all, iteLoop, bitSearch, bitList, nod//
//gcdlcm, isPrime, eratos, primeFactorize, Npow, combination, divisor, modinv, doubling, digitDP//
//dfs, bfs, dijkstra, WarshallFloyd, BellmanFord, UnionFind, Kruskal, RMQ, LCA//
ll i, j, k, l; ll N, M, K, H, W, L, X, Y, Z, R, Q;
ll MOD = 1000000007, INF = 1LL << 60, ans = 0, z = 0, o = 1;
vll flag, D; vpll path; vs C;
//***********//
void bfs(ll x,ll y) {
	queue<pll> Z;
	Z.push(mp(x,y));
	D[x][y] = 0;
	flag[x][y] = 1;
	pll u;
	while (!Z.empty()) {
		u = Z.front();
		flag[u.first][u.second] = 2;
		//debug(u.first, u.second,D[u.first][u.second]);
		Z.pop();
		ll nx, ny, px, py;
		ll cnt;
		px = u.first; py = u.second;
		nx = u.first; ny = u.second; cnt = K;
		//debug("hoge1");
		while (nx+1 <= H-1 && cnt>0) {
			//debug(nx, ny);
			if (C[nx + 1][ny] == '@') break;
			if (flag[nx + 1][ny]==2) break;
			if (D[px][py] + 1 <= D[nx + 1][ny]) {
				D[nx + 1][ny] = D[px][py] + 1;
				if (flag[nx+1][ny] == 0)Z.push(mp(nx + 1, ny));
				flag[nx+1][ny] = 1;
				nx++; cnt--;
			}
			else cnt = 0;
		}
		nx = u.first; ny = u.second; cnt = K;
		//debug("hoge2");
		while (nx - 1 >= 0 && cnt > 0) {
			if (C[nx - 1][ny] == '@') break;
			if (flag[nx - 1][ny]==2) break;
			if (D[px][py] + 1 <= D[nx - 1][ny]) {
				D[nx - 1][ny] = D[px][py] + 1;
				if (flag[nx-1][ny] == 0)Z.push(mp(nx - 1, ny));
				flag[nx - 1][ny] = 1;
				nx--; cnt--;
			}
			else cnt = 0;
		}
		nx = u.first; ny = u.second; cnt = K;
		//debug("hoge3");
		while (ny + 1 <= W-1 && cnt > 0) {
			if (C[nx][ny + 1] == '@') break;
			if (flag[nx][ny+1]==2) break;
			if (D[px][py] + 1 <= D[nx][ny+1]) {
				D[nx][ny+1] = D[px][py] + 1;
				if(flag[nx][ny + 1]==0)Z.push(mp(nx, ny+1));
				flag[nx][ny+1] = 1;
				ny++; cnt--;
			}
			else cnt = 0;
		}
		nx = u.first; ny = u.second; cnt = K;
		//debug("hoge4");
		while (ny - 1 >= 0 && cnt > 0) {
			if (C[nx][ny - 1] == '@') break;
			if (flag[nx][ny-1]==2) break;
			if (D[px][py] + 1 <= D[nx][ny - 1]) {
				D[nx][ny - 1] = D[px][py] + 1;
				if (flag[nx][ny - 1] == 0)Z.push(mp(nx, ny - 1));
				flag[nx][ny-1] = 1;
				ny--; cnt--;
			}
			else cnt = 0;
		}
	}
}
int main() { 
	cin >> H >> W >> K;
	ll P,Q,R,S;
	cin >> P >> Q >> R >> S;
	P--; Q--; R--; S--;
	C.resize(H);
	D.resize(H, vl(W));
	flag.resize(H, vl(W));
	for (i = 0; i < H; i++) {
		cin >> C[i];
		for (j = 0; j < W; j++) {
			D[i][j] = INF;
		}
	}
	bfs(P, Q);
	if (D[R][S] == INF) cout << -1;
	else cout << D[R][S];
}

Measured memory_bytes: 26784