#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <numeric>
#include <cmath>
#include <unordered_map>
#include <queue>
#include <deque>

using namespace std;
using ll = long long;

void _cin(){} template <class Head, class... Tail> void _cin(Head&& head, Tail&&... tail){ cin >> head; _cin(forward<Tail>(tail)...); }
void _cout(){ cout << "\n"; } template <class Head, class... Tail> void _cout(Head&& head, Tail&&... tail){ cout << head; _cout(forward<Tail>(tail)...); }
ll gcd(ll a, ll b){ return (b == 0) ? a : gcd(b, a % b); }
template<typename S, typename T> ostream& operator<<(ostream &os, const pair<S, T> &p){ cout << "[" << p.first << ", " << p.second << "]"; return os; }

#define Sq(x) (x)*(x)
#define For(i, n) for(int i = 0; i < (n); i ++)
#define Rep(n) For(_, n)
#define Range(c) c.begin(), c.end()
#define RevRange(c) c.rbegin(), c.rend()
#define Contains(c, x) (find(Range(c), x) != c.end())
#define Search(rb, re, x) distance(rb, find(rb, re, x))
#define Sort(a) sort(Range(a))
#define DeSort(a) sort(RevRange(a))
#define Reverse(c) reverse(Range(c))
#define Unique(a) a.erase(unique(Range(a)), a.end())
#define Cusum(T, xs, sxs) vector<T> sxs(xs.size()+1); For(i, (int)xs.size()) sxs[i+1] = sxs[i] + xs[i]
#define Cin(T, ...) T __VA_ARGS__; _cin(__VA_ARGS__)
#define Cins(T, n, xs) vector<T> xs(n); For(i, n) cin >> xs[i]
#define Cins2(T, n, xs, ys) vector<T> xs(n), ys(n); For(i, n) cin >> xs[i] >> ys[i]
#define Cins3(T, n, xs, ys, zs) vector<T> xs(n), ys(n), zs(n); For(i, n) cin >> xs[i] >> ys[i] >> zs[i]
#define Cinss(T, n, m, xs) Vec2(T, n, m, xs); For(i, n) For(j, m) cin >> xs[i][j]
#define Cinm(T, n, map) unordered_map<T, int> map; Rep(n){ Cin(T, x); map[x] ++; }
#define Cout(...) _cout(__VA_ARGS__)
#define Couts(xs) { for(const auto &e : xs) cout << e << " "; cout << "\n"; }
#define Coutyn(cond) Cout((cond) ? "yes" : "no")
#define CoutYn(cond) Cout((cond) ? "Yes" : "No")
#define CoutYN(cond) Cout((cond) ? "YES" : "NO")
#define Return(expr) { Cout(expr); return 0; }
#define vc vector
#define Mini(a, x) a = min(a, x)
#define Maxi(a, x) a = max(a, x)

// constexpr int MOD = 1e9+7;

int main(void){
    Cin(int, h, w, k);
    Cin(int, x1, y1, x2, y2);
    vc<string> s(h+2);
    s[0] = string(w+2, '@');
    For(i, h){
        Cin(string, t);
        s[i+1] = "@" + t + "@";
    }
    s.back() = string(w+2, '@');
    
    constexpr int inf = 1e9;
    vc<vc<int>> v(h+2, vc<int>(w+2, inf));
    v[x1][y1] = 0;
    
    deque<pair<int, int>> q;
    q.emplace_back(x1, y1);
    while(!q.empty()){
        auto [x, y] = q.front(); q.pop_front();
        // Cout(x, " ", y);
        if(x == x2 && y == y2){
            // For(i, h+2) Couts(v[i]);
            Return(v[x][y]);
        }
    
        for(int i = 1; i <= k; i ++){
            int xt = x+i, yt = y;
            if(s[xt][yt] == '@' || v[xt][yt] < v[x][y]+1) break;
            if(v[xt][yt] == v[x][y]+1) continue;
            v[xt][yt] = v[x][y]+1;
            q.emplace_back(xt, yt);
        }
        for(int i = 1; i <= k; i ++){
            int xt = x-i, yt = y;
            if(s[xt][yt] == '@' || v[xt][yt] < v[x][y]+1) break;
            if(v[xt][yt] == v[x][y]+1) continue;
            v[xt][yt] = v[x][y]+1;
            q.emplace_back(xt, yt);
        }
        for(int i = 1; i <= k; i ++){
            int xt = x, yt = y+i;
            if(s[xt][yt] == '@' || v[xt][yt] < v[x][y]+1) break;
            if(v[xt][yt] == v[x][y]+1) continue;
            v[xt][yt] = v[x][y]+1;
            q.emplace_back(xt, yt);
        }
        for(int i = 1; i <= k; i ++){
            int xt = x, yt = y-i;
            if(s[xt][yt] == '@' || v[xt][yt] < v[x][y]+1) break;
            if(v[xt][yt] == v[x][y]+1) continue;
            v[xt][yt] = v[x][y]+1;
            q.emplace_back(xt, yt);
        }
    }
    Cout(-1);
}


Measured memory_bytes: 21800