#include <algorithm>
#include <array>
#include <bitset>
#include <cassert>
#include <cfloat>
#include <chrono>
#include <climits>
#include <cmath>
#include <cstdio>
#include <deque>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <sstream>
#include <stack>
#include <stdexcept>
#include <unordered_map>
#include <unordered_set>
#include <vector>
using namespace std;

template <class T1, class T2>
ostream& operator << (ostream& out, const pair <T1, T2> p)
{
    out << '(' << p.first << ',' << p.second << ')';
    return out;
}

template <class T1, class T2>
istream& operator >> (istream& in, pair<T1, T2> &p)
{
    in >> p.first >> p.second;
    return in;
}

template <class T>
istream& operator >> (istream& in, vector<T> &v)
{
    for (T &x : v)
        in >> x;
    return in;
}

template <class T>
ostream& operator << (ostream& out, const vector<vector<T>> &v)
{
    for (const vector<T> &x : v)
        out << x << '\n';
    return out;
}

template <class T>
ostream& operator << (ostream& out, const vector<T> &v)
{
    for (const T &x : v)
        out << x << ' ';
    return out;
}

long long gcd (long long a, long long b)
{
    if (b > a)
        swap(a, b);
    return (b ? gcd(b, a % b) : a);
}

using ll   = long long;
using pii  = pair<int, int>;
using pll  = pair<long long, long long>;
using tiii = pair<pair<int, int>, int>;
using vi   = vector<int>;
using vl   = vector<long long>;
using vvi  = vector<vector<int>>;
using vvl  = vector<vector<long long>>;

#define F          first
#define S          second
#define First      first.first
#define Second     first.second
#define Third      second
#define mp         make_pair
#define rep(i,a,b) for (int i = (a); i < (b); i++)
#define per(i,b,a) for (int i = (b); i > (a); i--)
#define all(x)     x.begin(), x.end()
#define ret(x)     return cout << x, 0;
#define throwex    throw runtime_error ("Found the error.");

const int h = 1000000007;

signed main()
{
    ios::sync_with_stdio(false);
    #ifdef ONLINE_JUDGE
    cin.tie(nullptr);
    cout.tie(nullptr);
    cerr.setstate(ios::failbit);
    #endif

    int h, w, k;
    cin >> h >> w >> k;
    int x1, y1, x2, y2;
    cin >> x1 >> y1 >> x2 >> y2;
    x1--, y1--, x2--, y2--;
    vector<string> grid(h);
    cin >> grid;
    queue<pii> q;
    q.push({x1, y1});
    vvi vis_time(h, vi(w, INT_MAX));
    vis_time[x1][y1] = 0;
    vector<pii> dir{{1,0},{-1,0},{0,1},{0,-1}};
    while(!q.empty())
    {
        pii cur = q.front();
        q.pop();
        rep(i,0,4)
        {
            pii nex = cur;
            rep(_,0,k)
            {
                nex = {nex.F + dir[i].F, nex.S + dir[i].S};
                if(nex.F < 0 or nex.F == h
                or nex.S < 0 or nex.S == w)
                    break;
                if(grid[nex.F][nex.S] == '@' or vis_time[nex.F][nex.S] <= vis_time[cur.F][cur.S])
                    break;
                if(vis_time[nex.F][nex.S] == INT_MAX)
                {
                    vis_time[nex.F][nex.S] = vis_time[cur.F][cur.S] + 1;
                    q.push(nex);
                }
            }
        }
    }
    cout << (vis_time[x2][y2] == INT_MAX ? -1 : vis_time[x2][y2]);
}


Measured memory_bytes: 12124