#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <utility>
#include <tuple>
#include <cstdint>
#include <cstdio>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <deque>
#include <unordered_map>
#include <unordered_set>
#include <bitset>
#include <cctype>
#include <functional>
#include <ctime>
#include <cmath>
#include <limits>
#include <numeric>
#include <type_traits>
#include <iomanip>
#include <float.h>
#include <math.h>
using namespace std;
using ll = long long;


unsigned euclidean_gcd(unsigned a, unsigned b) {
    if (a < b) return euclidean_gcd(b, a);
    unsigned r;
    while ((r = a % b)) {
        a = b;
        b = r;
    }
    return b;
}

class UnionFind {
public:
    vector <ll> par;
    vector <ll> siz;
    UnionFind(ll sz_) : par(sz_), siz(sz_, 1LL) {
        for (ll i = 0; i < sz_; ++i) par[i] = i;
    }
    void init(ll sz_) {
        par.resize(sz_);
        siz.assign(sz_, 1LL);
        for (ll i = 0; i < sz_; ++i) par[i] = i;
    }
    ll root(ll x) {
        while (par[x] != x) {
            x = par[x] = par[par[x]];
        }
        return x;
    }
    bool merge(ll x, ll y) {
        x = root(x);
        y = root(y);
        if (x == y) return false;
        if (siz[x] < siz[y]) swap(x, y);
        siz[x] += siz[y];
        par[y] = x;
        return true;
    }

    bool issame(ll x, ll y) {
        return root(x) == root(y);
    }

    ll size(ll x) {
        return siz[root(x)];
    }
};

long long modpow(long long a, long long n, long long mod) {
    long long res = 1;
    while (n > 0) {
        if (n & 1) res = res * a % mod;
        a = a * a % mod;
        n >>= 1;
    }
    return res;
}

long long modinv(long long a, long long mod) {
    return modpow(a, mod - 2, mod);
}

int main() {
    ll h, w, k;
    cin >> h >> w >> k;
    ll a, b, cc, dd;
    cin >> a >> b >> cc >> dd;
    vector<vector<char>>z(h+2, vector<char>(w+2,'@'));
    for (int i = 1; i < h+1; i++) {
        string x;
        cin >> x;
        for (int j = 1; j < w + 1;j++) {
            z[i][j] = x[j - 1];
        }
    }
    queue<pair<ll, ll>> q;
    vector<vector<ll>>ans(h + 2, vector<ll>(w + 2, 123456789));
    q.push(make_pair(a,b));
    ans[a][b] = 0;
    while (!(q.empty())) {
        ll c = q.front().first;
        ll d = q.front().second;
        for (int i = 1; i < k+1; i++) {
            if (z[c + i][d] == '@' || ans[c + i][d] <= ans[c][d])break;
            if(ans[c + i][d]==123456789)q.push(make_pair(c + i, d));
            ans[c + i][d] = ans[c][d] + 1;
            
        }
        for (int i = 1; i < k + 1; i++) {
            if (z[c - i][d] == '@' || ans[c - i][d] <= ans[c][d])break;
            if (ans[c - i][d] == 123456789)q.push(make_pair(c - i, d));
            ans[c - i][d] = ans[c][d] + 1;
            
        }
        for (int i = 1; i < k + 1; i++) {
            if (z[c][d+i] == '@' || ans[c][d+i] <= ans[c][d])break;
            if (ans[c][d+i] == 123456789)q.push(make_pair(c, d+i));
            ans[c][d+i] = ans[c][d] + 1;
            
        }
        for (int i = 1; i < k + 1; i++) {
            if (z[c][d-i] == '@' || ans[c][d-i] <= ans[c][d])break;
            if (ans[c][d-i] == 123456789)q.push(make_pair(c, d-i));
            ans[c][d-i] = ans[c][d] + 1;
            
        }
        q.pop();
    }
    if (ans[cc][dd] == 123456789)ans[cc][dd] = -1;
    cout << ans[cc][dd] << endl;
}

Measured memory_bytes: 37468