#include <iostream>
#include <vector>
#include <map>
#include <set>
#include <unordered_set>
#include <unordered_map>
#include <stack>
#include <queue>
#include <algorithm>
#include <cassert>
#include <random>
#include <iomanip>
#include <bitset>
#define FOR(i, n, m) for(ll i = (n); i < (ll)(m); i++)
#define REP(i, n) FOR(i, 0, n)
#define ALL(v) v.begin(), v.end()
#define pb push_back
using namespace std;
using ll = long long;
using P = pair<ll, ll>;
constexpr ll inf = 1000000000;
constexpr ll mod = 1000000007;
constexpr long double eps = 1e-6;
 
template<typename T1, typename T2>
ostream& operator<<(ostream& os, pair<T1, T2> p) {
    os << to_string(p.first) << " " << to_string(p.second);
    return os;
}
template<typename T>
ostream& operator<<(ostream& os, vector<T>& v) {
    REP(i, v.size()) {
        if(i) os << " ";
        os << v[i];
    }
    return os;
}
 
struct modint {
    ll n;
public:
    modint(const ll n = 0) : n((n % mod + mod) % mod) {}
    static modint pow(modint a, int m) {
        modint r = 1;
        while(m > 0) {
            if(m & 1) { r *= a; }
            a = (a * a); m /= 2;
        }
        return r;
    }
    modint &operator++() { *this += 1; return *this; }
    modint &operator--() { *this -= 1; return *this; }
    modint operator++(int) { modint ret = *this; *this += 1; return ret; }
    modint operator--(int) { modint ret = *this; *this -= 1; return ret; }
    modint operator~() const { return (this -> pow(n, mod - 2)); } // inverse
    friend bool operator==(const modint& lhs, const modint& rhs) {
        return lhs.n == rhs.n;
    }
    friend bool operator<(const modint& lhs, const modint& rhs) {
        return lhs.n < rhs.n;
    }
    friend bool operator>(const modint& lhs, const modint& rhs) {
        return lhs.n > rhs.n;
    }
    friend modint &operator+=(modint& lhs, const modint& rhs) {
        lhs.n += rhs.n;
        if (lhs.n >= mod) lhs.n -= mod;
        return lhs;
    }
    friend modint &operator-=(modint& lhs, const modint& rhs) {
        lhs.n -= rhs.n;
        if (lhs.n < 0) lhs.n += mod;
        return lhs;
    }
    friend modint &operator*=(modint& lhs, const modint& rhs) {
        lhs.n = (lhs.n * rhs.n) % mod;
        return lhs;
    }
    friend modint &operator/=(modint& lhs, const modint& rhs) {
        lhs.n = (lhs.n * (~rhs).n) % mod;
        return lhs;
    }
    friend modint operator+(const modint& lhs, const modint& rhs) {
        return modint(lhs.n + rhs.n);
    }
    friend modint operator-(const modint& lhs, const modint& rhs) {
        return modint(lhs.n - rhs.n);
    }
    friend modint operator*(const modint& lhs, const modint& rhs) {
        return modint(lhs.n * rhs.n);
    }
    friend modint operator/(const modint& lhs, const modint& rhs) {
        return modint(lhs.n * (~rhs).n);
    }
};
istream& operator>>(istream& is, modint m) { is >> m.n; return is; }
ostream& operator<<(ostream& os, modint m) { os << m.n; return os; }
 
#define MAX_N 1010101
long long extgcd(long long a, long long b, long long& x, long long& y) {
    long long d = a;
    if (b != 0) {
        d = extgcd(b, a % b, y, x);
        y -= (a / b) * x;
    } else {
        x = 1; y = 0;
    }
    return d;
}
long long mod_inverse(long long a, long long m) {
    long long x, y;
    if(extgcd(a, m, x, y) == 1) return (m + x % m) % m;
    else return -1;
}
vector<long long> fact(MAX_N+1, inf);
long long mod_fact(long long n, long long& e) {
    if(fact[0] == inf) {
        fact[0]=1;
        if(MAX_N != 0) fact[1]=1;
        for(ll i = 2; i <= MAX_N; ++i) {
            fact[i] = (fact[i-1] * i) % mod;
        }
    }
    e = 0;
    if(n == 0) return 1;
    long long res = mod_fact(n / mod, e);
    e += n / mod;
    if((n / mod) % 2 != 0) return (res * (mod - fact[n % mod])) % mod;
    return (res * fact[n % mod]) % mod;
}
// return nCk
long long mod_comb(long long n, long long k) {
    if(n < 0 || k < 0 || n < k) return 0;
    long long e1, e2, e3;
    long long a1 = mod_fact(n, e1), a2 = mod_fact(k, e2), a3 = mod_fact(n - k, e3);
    if(e1 > e2 + e3) return 0;
    return (a1 * mod_inverse((a2 * a3) % mod, mod)) % mod;
}
 
using mi = modint;
 
mi mod_pow(mi a, ll n) {
    mi ret = 1;
    mi tmp = a;
    while(n > 0) {
        if(n % 2) ret *= tmp;
        tmp = tmp * tmp;
        n /= 2;
    }
    return ret;
}
 
ll gcd(ll a, ll b) {
    if (b == 0) return a;
    return gcd(b, a % b);
}

using ld = long double;

ll h, w, k;

ll to_num(ll i, ll j, ll dir) {
    return 4LL * (i * w + j) + dir;
}

vector<int> div(int num) {
    vector<int> ret(3);
    ret[2] = num % 4;
    num /= 4;
    ret[0] = num / w;
    ret[1] = num % w;
    return ret;
}

ll roof_modk(ll num) {
    if(num % k == 0) return num;
    else return num + (k - (num % k));
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cin >> h >> w >> k;
    pair<int, int> st, gl;
    cin >> st.first >> st.second >> gl.first >> gl.second;
    st.first--; st.second--;
    gl.first--; gl.second--;
    vector<string> pond(h);
    REP(i, h) cin >> pond[i];
    vector<ll> min_dist(h * w * 4, inf * inf);
    priority_queue<pair<ll, int>, vector<pair<ll, int>>, greater<pair<ll, int>>> q;
    min_dist[to_num(st.first, st.second, 0)] = 0; q.push({0, to_num(st.first, st.second, 0)});
    min_dist[to_num(st.first, st.second, 1)] = 0; q.push({0, to_num(st.first, st.second, 1)});
    min_dist[to_num(st.first, st.second, 2)] = 0; q.push({0, to_num(st.first, st.second, 2)});
    min_dist[to_num(st.first, st.second, 3)] = 0; q.push({0, to_num(st.first, st.second, 3)});
    int dx[] = {1, -1, 0, 0}, dy[] = {0, 0, 1, -1};
    while(!q.empty()) {
        auto [dist, num] = q.top();
        q.pop();
        if(min_dist[num] != dist) continue;
        auto info = div(num);
        int x = info[0], y = info[1], d = info[2];
        REP(i, 4) {
            int nx = x + dx[i], ny = y + dy[i];
            if(nx < 0 || nx >= h || ny < 0 || ny >= w) continue;
            ll ndist = ((d == i) ? dist : roof_modk(dist)) + 1;
            if(pond[nx][ny] != '@' && min_dist[to_num(nx, ny, i)] > ndist) {
                min_dist[to_num(nx, ny, i)] = ndist;
                q.push({ndist, to_num(nx, ny, i)});
            }
        }
    }
    ll ans = min({
        min_dist[to_num(gl.first, gl.second, 0)],
        min_dist[to_num(gl.first, gl.second, 1)],
        min_dist[to_num(gl.first, gl.second, 2)],
        min_dist[to_num(gl.first, gl.second, 3)]
    });
    if(ans == inf * inf) cout << -1 << endl;
    else cout << (ans % k == 0 ? (ans / k) : (ans / k + 1)) << endl;
    return 0;
}


Measured memory_bytes: 47740