#include <bits/stdc++.h>
using namespace std;
#define int long long
#define INF 1000000000000000000
#define MOD 998244353
int32_t main() {
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
int r, c, n, sr, sc, gr, gc;
cin >> r >> c >> n >> sr >> sc >> gr >> gc;
sr--; sc--; gr--; gc--;
string s[r];
for(int i = 0; i < r; i++) cin >> s[i];
vector<pair<pair<int, int>, int>> adj[r][c];
int dx[4] = {-1, 0, 0, 1};
int dy[4] = {0, -1, 1, 0};
for(int i = 0; i < r; i++) {
for(int j = 0; j < c; j++) {
for(int k = 0; k < 4; k++) {
int nx = i+dx[k], ny = j+dy[k];
if(nx < 0 || nx >= r || ny < 0 || ny >= c) continue;
if(s[nx][ny] == '#') continue;
adj[i][j].push_back({{nx, ny}, 0});
}
for(int k = -(n-1); k <= n-1; k++) {
for(int l = 0; l < 4; l++) {
int nx = i+dx[l]*n+k*dy[l], ny = j+dy[l]*n+k*dx[l];
if(nx < 0 || nx >= r || ny < 0 || ny >= c) continue;
adj[i][j].push_back({{nx, ny}, 1});
}
}
}
}
for(int i = -n; i <= n; i++) {
for(int j = -n; j <= n; j++) {
if(abs(i*j) == n*n || i == 0 && j == 0) continue;
int nx = gr+i, ny = gc+j;
if(nx < 0 || nx >= r || ny < 0 || ny >= c) continue;
adj[nx][ny].push_back({{gr, gc}, 1});
}
}
deque<pair<int, pair<int, int>>> dq;
int dist[r][c];
memset(dist, -1, sizeof(dist));
dist[sr][sc] = 0;
dq.push_front({0, {sr, sc}});
while(!dq.empty()) {
pair<int, pair<int, int>> cur = dq.front();
dq.pop_front();
if(cur.first != dist[cur.second.first][cur.second.second]) continue;
for(auto it : adj[cur.second.first][cur.second.second]) {
if(dist[it.first.first][it.first.second] == -1 || dist[it.first.first][it.first.second] > cur.first+it.second) {
dist[it.first.first][it.first.second] = cur.first+it.second;
if(it.second == 0) dq.push_front({cur.first+it.second, it.first});
else dq.push_back({cur.first+it.second, it.first});
}
}
}
cout << dist[gr][gc];
}
