#include<iostream>
#include<string>
#include<cstdio>
#include<vector>
#include<cmath>
#include<algorithm>
#include<functional>
#include<iomanip>
#include<queue>
#include<ciso646>
#include<random>
#include<map>
#include<set>
#include<bitset>
#include<stack>
#include<unordered_map>
#include<utility>
#include<cassert>
#include<complex>
#include<numeric>
using namespace std;

//#define int long long
typedef long long ll;

typedef unsigned long long ul;
typedef unsigned int ui;
constexpr ll mod = 1000000009;
const ll INF = mod * mod;
typedef pair<int, int>P;
#define stop char nyaa;cin>>nyaa;
#define rep(i,n) for(int i=0;i<n;i++)
#define per(i,n) for(int i=n-1;i>=0;i--)
#define Rep(i,sta,n) for(int i=sta;i<n;i++)
#define rep1(i,n) for(int i=1;i<=n;i++)
#define per1(i,n) for(int i=n;i>=1;i--)
#define Rep1(i,sta,n) for(int i=sta;i<=n;i++)
#define all(v) (v).begin(),(v).end()
typedef pair<ll, ll> LP;
typedef long double ld;
typedef pair<ld, ld> LDP;
const ld eps = 1e-12;
const ld pi = acos(-1.0);


struct modint {
	ll n;
	modint() :n(0) { ; }
	modint(ll m) :n(m) {
		if (n >= mod)n %= mod;
		else if (n < 0)n = (n%mod + mod) % mod;
	}
	operator int() { return n; }
};
bool operator==(modint a, modint b) { return a.n == b.n; }
modint operator+=(modint &a, modint b) { a.n += b.n; if (a.n >= mod)a.n -= mod; return a; }
modint operator-=(modint &a, modint b) { a.n -= b.n; if (a.n < 0)a.n += mod; return a; }
modint operator*=(modint &a, modint b) { a.n = ((ll)a.n*b.n) % mod; return a; }
modint operator+(modint a, modint b) { return a += b; }
modint operator-(modint a, modint b) { return a -= b; }
modint operator*(modint a, modint b) { return a *= b; }
modint operator^(modint a, int n) {
	if (n == 0)return modint(1);
	modint res = (a*a) ^ (n / 2);
	if (n % 2)res = res * a;
	return res;
}

ll inv(ll a, ll p) {
	return (a == 1 ? 1 : (1 - p * inv(p%a, a)) / a + p);
}
modint operator/(modint a, modint b) { return a * modint(inv(b, mod)); }

const int max_n = 1 << 18;
modint fact[max_n], factinv[max_n];
void init_f() {
	fact[0] = modint(1);
	for (int i = 0; i < max_n - 1; i++) {
		fact[i + 1] = fact[i] * modint(i + 1);
	}
	factinv[max_n - 1] = modint(1) / fact[max_n - 1];
	for (int i = max_n - 2; i >= 0; i--) {
		factinv[i] = factinv[i + 1] * modint(i + 1);
	}
}
modint comb(int a, int b) {
	if (a < 0 || b < 0 || a < b)return 0;
	return fact[a] * factinv[b] * factinv[a - b];
}
modint combP(int a, int b) {
	if (a < 0 || b < 0 || a < b)return 0;
	return fact[a] * factinv[a - b];
}
int dx[4] = { 1,0,-1,0 };
int dy[4] = { 0,1,0,-1 };

void solve() {
	int h, w, k; cin >> h >> w >> k;
	vector<vector<vector<P>>> nxt;
	nxt.resize(h);
	rep(i, h) {
		nxt[i].resize(w);
		rep(j, w) {
			nxt[i][j].resize(4);
			rep(k, 4) {
				nxt[i][j][k] = { i + dx[k],j + dy[k] };
			}
		}
	}
	int sx, sy, gx, gy; cin >> sx >> sy >> gx >> gy;
	sx--; sy--; gx--; gy--;
	vector<string> mp(h);
	rep(i, h)cin >> mp[i];
	vector<vector<int>> dist(h, vector<int>(w, mod));
	dist[sx][sy] = 0;
	queue<P> q;
	q.push({ sx,sy });

	function<P(int, int, int)> proc = [&](int x, int y, int d)->P{
		int nx = nxt[x][y][d].first;
		int ny = nxt[x][y][d].second;
		if (nx < 0 || ny < 0 || nx == h || ny == w)return nxt[x][y][d];
		if (mp[nx][ny] == '@')return nxt[x][y][d];
		if (dist[nx][ny] < mod)return nxt[x][y][d] = proc(nx, ny, d);
		return nxt[x][y][d];
	};
	while (!q.empty()) {
		int x = q.front().first;
		int y = q.front().second;
		q.pop();
		rep(d, 4) {
			int cx = x, cy = y;
			while (true) {
				P p = proc(cx, cy, d);
				int nx = p.first;
				int ny = p.second;
				if (nx < 0 || ny < 0 || nx == h || ny == w)break;
				if (mp[nx][ny] == '@')break;
				int dd = abs(x - nx) + abs(y - ny);
				if (dd > k)break;
				cx = nx, cy = ny;
				if (dist[x][y] + 1 < dist[cx][cy]) {
					dist[cx][cy] = dist[x][y] + 1;
					q.push({ cx,cy });
				}
			}
		}
	}
	if (dist[gx][gy] == mod)dist[gx][gy] = -1;
	cout << dist[gx][gy] << "\n";
}


signed main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	//cout << fixed << setprecision(6);
	//init_f();
	//init();
	//int t; cin >> t;rep(i,t)
	solve();
	stop
		return 0;
}


Measured memory_bytes: 86600