/*****/

#define TRUE true
#define FALSE false

#include <bits/stdc++.h>

/**/
#pragma GCC target("avx")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
/**/

using namespace std;
using ll = long long;
using ld = long double;
using pint = pair<int, int>;
using pll = pair<long long, long long>;
template <class T>
using vec = vector<T>;
template <class T>
using vec2 = vector<vector<T>>;
template <class T>
using vec3 = vector<vector<vector<T>>>;

constexpr int INF = numeric_limits<int>::max();
constexpr ll INFL = numeric_limits<ll>::max();
constexpr ll MOD = 1000000007; // 10^9+7

#ifdef TRUE

#define rep(i, n) for (ll i = 0, i##_len = (n); i < i##_len; ++i)
#define rep1(i, n) for (ll i = 1, i##_len = (n); i <= i##_len; ++i)
#define rrep(i, n) for (ll i = (n)-1; i >= 0; --i)
#define rrep1(i, n) for (ll i = (n); i > 0; --i)
#define step(i, a, n) for (ll i = (a), i##_len = (a) + (n); i < i##_len; ++i)
#define rstep(i, a, n) for (ll i = (a) + (n)-1, i##_len = (a); i >= i##_len; --i)
#define range(i, a, b) for (ll i = (a), i##_len = (b); i < i##_len; ++i)
#define rrange(i, a, b) for (ll i = (b)-1, i##_len = (a); i >= i##_len; --i)

std::string strMulti(const char c, const int n)
{
	std::string out = "";
	for (int i = 0; i < n; i++)
	{
		out += c;
	}
	return out;
}
std::string strMulti(const std::string t, const int n)
{
	std::string out = "";
	for (int i = 0; i < n; i++)
	{
		out += t;
	}
	return out;
}
std::string tab(const int n)
{
	return strMulti('\t', n);
}
std::string join(const vector<string> &v, const char *delim = 0)
{
	std::string s;
	if (!v.empty())
	{
		s += v[0];
		for (decltype(v.size()) i = 1, c = v.size(); i < c; ++i)
		{
			if (delim)
				s += delim;
			s += v[i];
		}
	}
	return s;
}

string to_string(string &s) { return '"' + s + '"'; }
string to_string(char &c) { return string({'\'', c, '\''}); }
template <class T1, class T2>
string to_string(pair<T1, T2> p)
{
	return "(" + to_string(p.first) + ", " + to_string(p.second) + ")";
}
template <class Tuple, size_t... I>
string _to_string_tuple(Tuple &&t, std::index_sequence<I...>)
{
	vector<string> texts = {to_string(std::get<I>(t))...};
	return "(" + join(texts, ", ") + ")";
}
template <class... Args>
string to_string(tuple<Args...> t)
{
	using Tuple = tuple<Args...>;
	return _to_string_tuple(std::forward<Tuple>(t),
							std::make_index_sequence<std::tuple_size<std::decay_t<Tuple>>::value>{});
}
template <class T>
string to_string(vector<T> ar)
{
	vector<string> texts(ar.size());
	for (size_t i = 0; i < ar.size(); ++i)
	{
		texts[i] = to_string(ar[i]);
	}
	return "{" + join(texts, ", ") + "}";
}
template <class T>
string to_string(initializer_list<T> il)
{
	vector<string> texts(il.size());
	size_t i = 0;
	for (T v : il)
	{
		texts[i] = to_string(v);
		i++;
	}
	return "{" + join(texts, ", ") + "}";
}

#ifdef DEBUG_BUILD
#define debugvar(x) debugln(#x, (x))
#define debugvartab(x, t) debugln(tab(t) + #x, (x))
void debug(string name)
{
	std::cerr << name;
}
void debugln(string name)
{
	std::cerr << name << '\n';
}
template <class T>
void debug(string name, T v)
{
	std::cerr << name << " = " << to_string(v);
}
template <class T>
void debugln(string name, T v)
{
	std::cerr << name << " = " << to_string(v) << '\n';
}
template <class T>
void debug(string name, initializer_list<T> il)
{
	std::cerr << name << " = " << to_string(il);
}
template <class T>
void debugln(string name, initializer_list<T> il)
{
	std::cerr << name << " = " << to_string(il) << '\n';
}
template <class... Args>
void debug(string name, Args... args)
{
	std::cerr << name << " = " << to_string(tuple<Args...>(args...));
}
template <class... Args>
void debugln(string name, Args... args)
{
	std::cerr << name << " = " << to_string(tuple<Args...>(args...)) << '\n';
}
#else
#define debugvar(x)
#define debugvartab(x, t)
void debug(string name)
{
}
void debugln(string name) {}
template <class T>
void debug(string name, T v) {}
template <class T>
void debugln(string name, T v) {}
template <class T>
void debug(string name, initializer_list<T> il) {}
template <class T>
void debugln(string name, initializer_list<T> il) {}
template <class... Args>
void debug(string name, Args... args) {}
template <class... Args>
void debugln(string name, Args... args) {}
#endif

#define all(x) (x).begin(), (x).end()
#define pair(a, b) make_pair(a, b)

template <class T>
bool chmax(T &a, const T b)
{
	if (a < b)
	{
		a = b;
		return true;
	}
	return false;
}
template <class T>
bool chmin(T &a, const T b)
{
	if (a > b)
	{
		a = b;
		return true;
	}
	return false;
}
template <class T>
T divup(const T a, const T b)
{
	if (a % b == 0)
	{
		return a / b;
	}
	return a / b + 1;
}
template <class T>
bool cmp_2nd(pair<T, T> a, pair<T, T> b)
{
	if (a.second != b.second)
	{
		return a.second < b.second;
	}
	return a.first < b.first;
}
ll modpow(ll x, ll n, const ll &p)
{
	ll ret = 1;
	while (n > 0)
	{
		if (n & 1)
		{
			(ret *= x) %= p;
		}
		(x *= x) %= p;
		n >>= 1;
	}
	return ret;
}
template <class T>
T modinv(T a, const T &p)
{
	T b = p, u = 1, v = 0;
	while (b)
	{
		T t = a / b;
		a -= t * b;
		swap(a, b);
		u -= t * v;
		swap(u, v);
	}
	u %= p;
	if (u < 0)
	{
		u += p;
	}
	return u;
}
template <class T>
T math_P(T m, T n)
{
	T ret = 1;
	for (T i = m; i > m - n; i--)
	{
		ret *= i;
	}
	return ret;
}
template <class T>
T math_C(T m, T n)
{
	T ret = math_P(m, n);
	for (T i = 2; i <= n; i++)
	{
		ret /= i;
	}
	return ret;
}
ll extended_euclidean(ll u, ll v)
{
	ll r0 = u;
	ll r1 = v;
	ll s0 = 1;
	ll s1 = 0;
	ll t0 = 0;
	ll t1 = 1;
	while (r1 != 0)
	{
		ll q = r0 / r1;
		ll r = r0 - q * r1;
		ll s = s0 - q * s1;
		ll t = t0 - q * t1;
		r0 = r1;
		s0 = s1;
		t0 = t1;
		r1 = r;
		s1 = s;
		t1 = t;
	}
	if (t0 < 0)
	{
		return t0 + u;
	}
	else
	{
		return t0;
	}
}
ll math_C_mod(ll n, ll c, const ll &p)
{
	ll upe = 1;
	ll dow = 1;
	for (ll i = 1; i < c + 1; ++i)
	{
		upe = upe * n % p;
		dow = dow * i % p;
		n -= 1;
	}
	return (upe * extended_euclidean(p, dow)) % p;
}
template <class T>
T math_gcd(T a, T b)
{
	if (b == 0)
	{
		return a;
	}
	else
	{
		return math_gcd(b, a % b);
	}
}
template <class T>
T math_lcm(T a, T b) { return a / math_gcd(a, b) * b; }
template <class T>
T SumStep(T a, T n, T d) { return n * (2 * a + (n - 1) * d) / 2; }
template <class T>
T SumRange(T a, T b, T d) { return SumStep(a, (b - a) / d, d); }

#endif

/*****/

template <class T>
class Point
{
public:
	T x = 0;
	T y = 0;

	Point() = default;

	Point(T x, T y) { set(x, y); }

	Point(const Point<T> &p) { set(p.x, p.y); }

	void set(T _x, T _y)
	{
		x = _x;
		y = _y;
	}

	void move(T dx, T dy)
	{
		x += dx;
		y += dy;
	}

	Point<T> up1() const
	{
		return Point(x, y + 1);
	}
	Point<T> down1() const { return Point(x, y - 1); }
	Point<T> right1() const { return Point(x + 1, y); }
	Point<T> left1() const { return Point(x - 1, y); }

	array<Point<T>, 4> adjoin() const
	{
		return {
			this->up1(),
			this->down1(),
			this->right1(),
			this->left1(),
		};
	}

	bool isWithin(T w, T h) const { return 0 <= x && x < w && 0 <= y && y < h; }
};

void Main()
{
	int H, W, K;
	cin >> H >> W >> K;
	Point<int> Stt, End;
	vec2<int> C(H, vec<int>(W, INF));
	{
		int x1, y1, x2, y2;
		cin >> y1 >> x1 >> y2 >> x2;
		x1--;
		x2--;
		y1--;
		y2--;
		Stt.set(x1, y1);
		C[y1][x1] = 0;
		End.set(x2, y2);
	}
	rep(y, H) rep(x, W)
	{
		char ch;
		cin >> ch;
		if (ch == '@')
			C[y][x] = -1;
	}

	queue<Point<int>> Q;
	Q.push(Stt);
	while (!Q.empty() && C[End.y][End.x] == INF)
	{
		Point<int> &now = Q.front();
		int &nowc = C[now.y][now.x];

		rep(d, 4)
		{
			rep1(i, K)
			{
				Point<int> to(now);
				switch (d)
				{
				case 0:
					to.x += i;
					break;
				case 1:
					to.x -= i;
					break;
				case 2:
					to.y += i;
					break;
				case 3:
					to.y -= i;
					break;
				}
				if (to.isWithin(W, H))
				{
					if (C[to.y][to.x] < nowc + 1)
					{
						break;
					}
					if (chmin(C[to.y][to.x], nowc + 1))
					{
						Q.push(to);
					}
				}
			}
		}

		Q.pop();
	}

#ifdef DEBUG_BUILD
	rep(y, H)
	{
		debugln(to_string(y), C[y]);
	}
#endif

	if (C[End.y][End.x] == INF)
		cout << "-1" << endl;
	else
		cout << C[End.y][End.x] << endl;
}

/*****/

int main()
{
	std::ios::sync_with_stdio(false);
	std::cin.tie(0);

	std::cout << std::fixed << std::setprecision(10);

	Main();
	std::cerr << flush;
	std::cout << flush;

	return 0;
}


Measured memory_bytes: 11052