#include <bits/stdc++.h>
using namespace std;
#define sz(x) int(x.size())
const int INF = 1e9;
struct STree {
int n;
vector<bool> st;
STree(int _n) {
n = 1;
while (n < _n) n *= 2;
st.assign(2 * n, false);
for (int i = 0; i < _n; i++) {
st[n + i] = true;
}
for (int i = n - 1; i > 0; i--) {
st[i] = st[2 * i] || st[2 * i + 1];
}
}
void update(int p) {
st[p += n] = false;
while (p /= 2) st[p] = st[2 * p] || st[2 * p + 1];
}
int find(int u) {
while (u < n) {
u *= 2;
if (!st[u]) u++;
}
return u - n;
}
int lower_bound(int x) {
int l = x + n, r = 2 * n;
int u = -1;
while (l < r) {
if (l & 1) {
if (st[l]) return find(l);
l++;
}
if (r & 1) {
r--;
if (st[r]) u = r;
}
l /= 2, r /= 2;
}
if (u == -1) return n;
return find(u);
}
};
const vector<int> dx = {0, 1, 0, -1};
const vector<int> dy = {1, 0, -1, 0};
int main() {
ios::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
int h, w, k, s_r, s_c, g_r, g_c;
cin >> h >> w >> k >> s_r >> s_c >> g_r >> g_c;
--s_r, --s_c, --g_r, --g_c;
vector<string> g(h);
for (int i = 0; i < h; i++) cin >> g[i];
vector<STree> row(h, STree(w));
vector<STree> col(w, STree(h));
vector<vector<bool>> vis(h, vector<bool>(w, false));
vector<vector<int>> dist(h, vector<int>(w, INF));
deque<tuple<int, int, int>> dq;
const auto push = [&](int x, int y) {
assert(!vis[x][y]);
dq.emplace_front(x, y, 0);
vis[x][y] = true;
row[x].update(y);
col[y].update(x);
};
dist[s_r][s_c] = 0;
push(s_r, s_c);
while (!dq.empty()) {
auto [x, y, op] = dq.front();
dq.pop_front();
if (op == 0) {
for (int i = 0; i < 4; i++) {
int nx = x + dx[i], ny = y + dy[i];
if (nx >= 0 && nx < h && ny >= 0 && ny < w && !vis[nx][ny] && g[nx][ny] == '.') {
dist[nx][ny] = dist[x][y];
push(nx, ny);
}
}
dq.emplace_back(x, y, 1);
} else {
if (abs(x - g_r) <= k && abs(y - g_c) <= k && abs(x - g_r) + abs(y - g_c) < 2 * k && !vis[g_r][g_c]) {
dist[g_r][g_c] = dist[x][y] + 1;
push(g_r, g_c);
}
if (x - k >= 0) {
int l = max(y - k + 1, 0);
int r = min(y + k, w);
while (true) {
int p = row[x - k].lower_bound(l);
if (p < r) {
dist[x - k][p] = dist[x][y] + 1;
push(x - k, p);
} else break;
}
}
if (x + k < h) {
int l = max(y - k + 1, 0);
int r = min(y + k, w);
while (true) {
int p = row[x + k].lower_bound(l);
if (p < r) {
dist[x + k][p] = dist[x][y] + 1;
push(x + k, p);
} else break;
}
}
if (y - k >= 0) {
int l = max(x - k + 1, 0);
int r = min(x + k, h);
while (true) {
int p = col[y - k].lower_bound(l);
if (p < r) {
dist[p][y - k] = dist[x][y] + 1;
push(p, y - k);
} else break;
}
}
if (y + k < w) {
int l = max(x - k + 1, 0);
int r = min(x + k, h);
while (true) {
int p = col[y + k].lower_bound(l);
if (p < r) {
dist[p][y + k] = dist[x][y] + 1;
push(p, y + k);
} else break;
}
}
}
}
cout << dist[g_r][g_c] << '\n';
return 0;
}
