#define _CRT_SECURE_NO_WARNINGS
#pragma comment(linker, "/stack:512000000")
#include<utility>
#include<iostream>
#include<fstream>
#include<vector>
#include<array>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cmath>
#include<ctime>
#include<functional>
#include<random>
#include<climits>
#include<queue>
#include<stack>
#include<deque>
#include<bitset>
#include<map>
#include<set>
#include<unordered_map>
#include<unordered_set>
#include<cassert>
#include<ccomplex>
#include<chrono>

#ifdef ONLINE_JUDGE
#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,tune=native")
#pragma GCC optimize("unroll-loops")
#define int128 __int128
#else
#define int128 long long
#endif

#define all(x) x.begin(), x.end()
#define make_unique(x) sort(all((x))); (x).resize(unique(all((x))) - (x).begin())
#define mp make_pair
#define X first
#define Y second

using namespace std;

using ll = long long;
using ull = unsigned long long;
using ld = long double;
mt19937_64 gen(time(nullptr));


struct custom_hash {
    static uint64_t splitmix64(uint64_t x) {
        // http://xorshift.di.unimi.it/splitmix64.c
        x += 0x9e3779b97f4a7c15;
        x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
        x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
        return x ^ (x >> 31);
    }

    size_t operator()(uint64_t x) const {
        static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
        return splitmix64(x + FIXED_RANDOM);
    }
};

ll mod = 1e9 + 7;

namespace {
    ll mul(ll a, ll b) {
        ll val = a * b - (ll)((ld)a * b / mod) * mod;
        if (val < 0) val += mod;
        if (val >= mod) val -= mod;
        return val;
    }
    ll poww(ll a, ll b) {
        ll val = 1;
        a %= mod;
        while (b > 0) {
            if (b % 2) val = mul(a, val);
            a = mul(a, a);
            b >>= 1;
        }
        return val % mod;
    }
    ll inv(ll a) {
        return poww(a, mod - 2);
    }
}

ll const maxn = 2e5 + 5;

ll cnt[21];

signed main() {
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    //freopen("output.txt", "w", stdout);

    ll n, m, k; cin >> n >> m >> k;
    ll x1, y1, x2, y2; cin >> x1 >> y1 >> x2 >> y2;
    x1--, y1--, x2--, y2--;


    vector<vector<char>>a(n, vector<char>(m));
    vector<vector<char>>left(n, vector<char>(m));
    vector<vector<char>>right(n, vector<char>(m));
    vector<vector<char>>up(n, vector<char>(m));
    vector<vector<char>>down(n, vector<char>(m));
    vector<vector<char>>used(n, vector<char>(m));
    vector<vector<ll>>d(n, vector<ll>(m));

    for (ll i = 0; i < n; i++) {
        for (ll j = 0; j < m; j++) {
            cin >> a[i][j];
        }
    }
    queue<pair<ll, ll>> q;
    q.push({ x1,y1 });
    used[x1][y1] = 1;
    while (!q.empty()) {
        auto p = q.front();
        q.pop();
        ll x = p.X, y = p.Y;
        for (ll xx = x + 1; xx <= x + k; xx++) {
            if (xx >= n or down[xx][y] or a[xx][y] == '@') {
                break;
            }
            if (used[xx][y] and d[xx][y] < d[x][y] + 1) break;
            used[xx][y] = 1;
            down[xx][y] = 1;
            d[xx][y] = d[x][y] + 1;
            q.push({ xx, y });
        }
        for (ll yy = y + 1; yy <= y + k; yy++) {
            if (yy >= m or right[x][yy] or a[x][yy] == '@') {
                break;
            }
            if (used[x][yy] and d[x][yy] < d[x][y] + 1) break;
            used[x][yy] = 1;
            right[x][yy] = 1;
            d[x][yy] = d[x][y] + 1;
            q.push({ x, yy });
        }
        for (ll xx = x - 1; xx >= x - k; xx--) {
            if (xx < 0 or up[xx][y] or a[xx][y] == '@') {
                break;
            }
            if (used[xx][y] and d[xx][y] < d[x][y] + 1) break;
            used[xx][y] = 1;
            up[xx][y] = 1;
            d[xx][y] = d[x][y] + 1;
            q.push({ xx, y });
        }
        for (ll yy = y - 1; yy >= y - k; yy--) {
            if (yy < 0 or left[x][yy] or a[x][yy] == '@') {
                break;
            }
            if (used[x][yy] and d[x][yy] < d[x][y] + 1) break;
            used[x][yy] = 1;
            left[x][yy] = 1;
            d[x][yy] = d[x][y] + 1;
            q.push({ x, yy });
        }
    }

    if (d[x2][y2]) cout << d[x2][y2];
    else cout << -1;
    return 0;
}

/*

*/

Measured memory_bytes: 25720