#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define ll long long
#define ld long double
#define ull unsigned long long
#define ff first
#define ss second
#define pii pair<int,int>
#define pll pair<long long, long long>
#define vi vector<int>
#define vl vector<long long>
#define pb push_back
#define rep(i, b) for(int i = 0; i < (b); ++i)
#define rep2(i,a,b) for(int i = a; i <= (b); ++i)
#define rep3(i,a,b,c) for(int i = a; i <= (b); i+=c)
#define count_bits(x) __builtin_popcountll((x))
#define all(x) (x).begin(),(x).end()
#define siz(x) (int)(x).size()
#define forall(it,x) for(auto& it:(x))
using namespace __gnu_pbds;
using namespace std;
typedef tree<int, null_type, less<int>, rb_tree_tag,tree_order_statistics_node_update> ordered_set;
//mt19937 mt;void random_start(){mt.seed(chrono::time_point_cast<chrono::milliseconds>(chrono::high_resolution_clock::now()).time_since_epoch().count());}
//ll los(ll a, ll b) {return a + (mt() % (b-a+1));}
const int INF = 1e9+50;
const ll INF_L = 1e18+40;
const ll MOD = 1e9+7;
int r,c,n;
string plane[6'000'001];
int dist[12'000'001];
vector<pii> dir4 = {{1,0},{-1,0},{0,1},{0,-1}};
vector<pii> dir8 = {{1,0},{-1,0},{0,1},{0,-1},{1,1},{1,-1},{-1,1},{-1,-1}};
int main()
{
ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
//random_start();
cin >> r >> c >> n;
int sx, sy, ex, ey;
cin >> sx >> sy >> ex >> ey;
sx--;
sy--;
ex--;
ey--;
int beg_cell = sx * c + sy;
int end_cell = ex * c + ey;
rep(i,r) cin >> plane[i];
rep(i,12'000'001) dist[i] = 1e9;
priority_queue<pair<pii,pii>,vector<pair<pii,pii>>,greater<pair<pii,pii>>> q;
q.push({{0,0},{sx,sy}});
while(!q.empty())
{
pair<pii,pii> t = q.top();
q.pop();
int cell = t.ss.ff * c + t.ss.ss + c*r * t.ff.ss;
if(dist[cell] != 1e9) continue;
dist[cell] = t.ff.ff;
if(t.ff.ss == 0)
{
forall(d,dir4)
{
int new_x = t.ss.ff + d.ff;
int new_y = t.ss.ss + d.ss;
if(new_x >= 0 && new_x < r && new_y >= 0 && new_y < c)
{
if(plane[new_x][new_y] == '.')
{
q.push({{t.ff.ff,0},{new_x,new_y}});
}
q.push({{t.ff.ff+1,1},{new_x,new_y}});
}
}
}
else
{
forall(d,dir8)
{
int new_x = t.ss.ff + d.ff;
int new_y = t.ss.ss + d.ss;
if(new_x >= 0 && new_x < r && new_y >= 0 && new_y < c)
{
q.push({{t.ff.ff+1,1},{new_x,new_y}});
}
}
if(t.ff.ff % n == 0)
{
q.push({{t.ff.ff,0},t.ss});
}
}
}
cout << (min(dist[end_cell],dist[end_cell+r*c]) + n-1) / n;
}
