#include <cstdio>
#include <stdio.h>
#include <stdbool.h>
#include <iostream>
#include <map>
#include <vector>
#include <climits>
#include <stack>
#include <string>
#include <queue>
#include <algorithm>
#include <set>
#include <unordered_set>
#include <unordered_map>
#include <cmath>
#include <cctype>
#include <bitset>
#include <iomanip>
#include <cstring>
#include <numeric>
#include <cassert>
#include <random>
#include <chrono>
#include <fstream>
using namespace std;
#define int long long
#define pii pair<int, int>
#define mp make_pair
#define pb push_back
#define fi first
#define se second
int dy[8]={0, 0, -1, 1, -1, 1, -1, 1};
int dx[8]={1, -1, 0, 0, -1, 1, 1, -1};
int32_t main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int n, m, k, sx, sy, ex, ey;
cin>>n>>m>>k>>sx>>sy>>ex>>ey, --sx, --sy, --ex, --ey;
vector<string> graph(n);
for (int i=0; i<n; ++i)cin>>graph[i];
vector<vector<bool> > visited(n, vector<bool>(m, 0));
vector<vector<pii> > dist(n, vector<pii>(m, mp(LLONG_MAX/2, LLONG_MAX/2)));
priority_queue<pair<pii, pii>, vector<pair<pii, pii> >, greater<pair<pii, pii> > > pq;
dist[sx][sy]=mp(0, k-1);
pq.push(mp(mp(0, k-1), mp(sx, sy)));
while (pq.size()){
int x=pq.top().se.fi, y=pq.top().se.se;
pq.pop();
if (visited[x][y])continue;
visited[x][y]=1;
for (int i=0; i<4; ++i){
int nx=x+dx[i], ny=y+dy[i];
if (nx<0||ny<0||nx>=n||ny>=m||visited[nx][ny])continue;
if (graph[nx][ny]=='.'&&mp(dist[x][y].fi, k-1)<dist[nx][ny]){
dist[nx][ny]=mp(dist[x][y].fi, k-1);
pq.push(mp(mp(dist[x][y].fi, k-1), mp(nx, ny)));
}
if (mp(dist[x][y].fi+1, 0ll)<dist[nx][ny]){
dist[nx][ny]=mp(dist[x][y].fi+1, 0ll);
pq.push(mp(mp(dist[x][y].fi+1, 0ll), mp(nx, ny)));
}
}
if (dist[x][y].se!=k-1)for (int i=0; i<8; ++i){
int nx=x+dx[i], ny=y+dy[i];
if (nx<0||ny<0||nx>=n||ny>=m||visited[nx][ny])continue;
if (mp(dist[x][y].fi, dist[x][y].se+1)<dist[nx][ny]){
dist[nx][ny]=mp(dist[x][y].fi, dist[x][y].se+1);
pq.push(mp(mp(dist[x][y].fi, dist[x][y].se+1), mp(nx, ny)));
}
}
}
cout<<dist[ex][ey].fi;
}
