#pragma GCC optimize("O3")
#include <iostream>
#include <vector>
#include <string>
#include <math.h>
#include <cmath>
#include <iomanip>
#include <cstdio>
#include <algorithm>
#include <numeric>
#include <map>
#include <set>
#include <queue>
#include <stack>
#include <deque>
#include <bitset>
#include <cstring>
#include <unordered_map>

using namespace std;
typedef int ll;

#define endl '\n'
typedef pair<ll, pair<ll, ll>> pll;

priority_queue<pll, vector<pll>, greater<pll>> q;
ll n, r, c;

void check(int x, int y, int d, vector<vector<ll>> &dist, vector<string> &a){
    if(x >= 1 && y >= 1 && x <= r && y <= c && d < dist[x][y] && a[x][y] == '.'){
        dist[x][y] = d;
        q.push({d, {x, y}});
    }
}

int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    
    cin >> r >> c >> n;
    
    ll s1, s2, f1, f2;
    cin >> s1 >> s2 >> f1 >> f2;
    
    vector<string> a(r + 1);
    for(int i = 1; i <= r; i++){
        cin >> a[i];
        
        a[i] = "#" + a[i];
    }
    
    vector<set<ll>> st(r + 1);
    
    for(int i = 1; i <= r; i++){
        for(int j = 1; j <= c; j++){
            if(i != s1 || j != s2)
                st[i].insert(j);
        }
    }
    
    q.push({0, {s1, s2}});
    vector<vector<bool>> used(r + 1, vector<bool> (c + 1));
    vector<vector<ll>> dist(r + 1, vector<ll> (c + 1, 1e9));
    
    dist[s1][s2] = 0;
    vector<int> roll;
    
    while(!q.empty()){
        auto v = q.top();
        q.pop();
        
        int x = v.second.first, y = v.second.second;
        if(used[x][y])
            continue;
        
        if(x == f1 && y == f2)
            break;
        
        used[x][y] = 1;
        check(x - 1, y, v.first, dist, a);
        check(x + 1, y, v.first, dist, a);
        check(x, y - 1, v.first, dist, a);
        check(x, y + 1, v.first, dist, a);
        
        for(int x2 = max(1, x - n); x2 <= min(r, x + n); x2++){
            auto u = st[x2].lower_bound(y - n);
            
            roll.clear();
            while(u != st[x2].end() && (*u) <= y + n){
                if((abs(x2 - x) < n || abs(y - *u) < n) && v.first + 1 < dist[x2][(*u)]){
                    dist[x2][*u] = v.first + 1;
                    q.push({v.first + 1, {x2, *u}});
                    
                    roll.push_back(*u);
                }
                u++;
            }
            
            for(auto i: roll){
                st[x2].erase(i);
            }
        }
    }
    
    cout << dist[f1][f2] << endl;
    
    return 0;
}