#include <algorithm>
#include <iostream>
#include <vector>
#include <math.h>
#include <set>
#include <map>
#include <string>
#include <stack>
#include <queue>
#include <iomanip>
#include <numeric>
#include <tuple>
#include <bitset>
#include <complex>
#include <unistd.h>
#include <cassert>
#include <cctype>
#include <random>
#include <time.h>
#include <functional>
#define _USE_MATH_DEFINES
#define _GLIBCXX_DEBUG
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> plglg;
typedef pair<double, ll> pdlg;
typedef tuple<int, int, int> tiii;
typedef tuple<ll, ll, ll> tlglglg;
typedef tuple<ll, ll, ll, ll> tlglglglg;
typedef tuple<ll, ll, ll, ll, ll> tlg5;
typedef tuple<double, double, double> tddd;
typedef complex<double> xy_t;
typedef vector<ll> vll;
typedef vector< vector<ll> > matrix;
typedef unsigned int uint;
typedef unsigned long long ull;
template <class T> using V = vector<T>;
template <class T> using VV = V<V<T>>;
template <class T> using VVV = V<VV<T>>;
#define REP(i, x, y) for(ll i = (ll)x; i < (ll)y; i++)
#define DREP(i, x, y, d) for(ll i = (ll)x; i < (ll)y; i += (ll)d)
#define PER(i, x, y) for(ll i = (ll)x; i > (ll)y; i--)
#define DPER(i, x, y, d) for(ll i = (ll)x; i > (ll)y; i -= (ll)d)
int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};
double pi = 3.141592653589793;
ll mod = 1000000007;
int intmax = 2147483647;
int intmin = -2147483648;
ll llmax = 9223372036854775807;
ll llmin = -9223372036854775807;
int iinf = intmax / 8;
ll inf = llmax / 8;
double eps = 1e-12;
void yesno(bool ok, string yes = "Yes", string no = "No") {
    if (ok) {
        cout << yes << endl;
    } else {
        cout << no << endl;
    }
}

bool cmp (plglg p, plglg q) {
    if (p.first == q.first) {
        return p.second > q.second;
    } else {
        return p.first < q.first;
    }
}

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    ll H, W, K;
    cin >> H >> W >> K;
    bool bo[H][W];
    plglg d[H][W][4];
    ll x1, y1, x2, y2;
    cin >> x1 >> y1 >> x2 >> y2;
    x1--;
    y1--;
    x2--;
    y2--;
    REP(i, 0, H) {
        string s;
        cin >> s;
        REP(j, 0, W) {
            if (s[j] == '@') {
                bo[i][j] = false;
            } else {
                bo[i][j] = true;
            }
        }
    }
    REP(i, 0, H) {
        REP(j, 0, W) {
            fill(d[i][j], d[i][j] + 4, plglg(inf, 0));
        }
    }
    auto c = [](tlg5 l, tlg5 r) {if (get<0>(l) == get<0>(r)) {
        return get<1>(l) < get<1>(r);
    } else {
        return get<0>(l) > get<0>(r);
    }};
    priority_queue<tlg5, V<tlg5>, decltype(c) > que(c);
    REP(i, 0, 4) {
        que.push(tlg5(0, 0, x1, y1, i));
        d[x1][y1][i] = plglg(0, 0);
    }
    while (!que.empty()) {
        tlg5 t = que.top();
        ll dis = get<0>(t);
        ll rem = get<1>(t);
        ll x = get<2>(t);
        ll y = get<3>(t);
        ll dir = get<4>(t);
        que.pop();
        if (cmp(d[x][y][dir], plglg(dis, rem))) {
            continue;
        }
        REP(i, 0, 4) {
            ll newx = x + dx[i];
            ll newy = y + dy[i];
            if (newx < 0 || newx >= H || newy < 0 || newy >= W) {
                continue;
            }
            if (!bo[newx][newy]) {
                continue;
            }
            ll newdis = (i == dir && rem > 0) ? dis : dis + 1;
            ll newrem = (i == dir && rem > 0) ? rem - 1 : K - 1;
            if (cmp(plglg(newdis, newrem), d[newx][newy][i])) {
                d[newx][newy][i] = plglg(newdis, newrem);
                que.push(tlg5(newdis, newrem, newx, newy, i));
            }
        }
    }
    // REP(i, 0, H) {
    //     REP(j, 0, W) {
    //         REP(k, 0, 4) {
    //             cout << d[i][j][k].first << " " << d[i][j][k].second << " aaa ";
    //         }
    //     }
    //     cout << " bbb " << endl;
    // }
    ll ans = inf;
    REP(i, 0, 4) {
        ans = min(ans, d[x2][y2][i].first);
    }
    if (ans < inf) {
        cout << ans << endl;
    } else {
        cout << -1 << endl;
    }
}


Measured memory_bytes: 77112