#include <bits/stdc++.h>
using namespace std;
const int dx[] = {1, 0, -1, 0},
dy[] = {0, 1, 0, -1};
struct DSU {
vector<int> id;
DSU(int n) : id(n, -1) {}
int root(int u) { return id[u] < 0 ? u : id[u] = root(id[u]); }
void add(int u, int v) {
u = root(u); v = root(v);
if (u == v) return;
id[u] += id[v];
id[v] = u;
}
};
int32_t main() {
cin.tie(0)->sync_with_stdio(0);
int r, c, n; cin >> r >> c >> n;
int Sr, Sc; cin >> Sr >> Sc;
int Gr, Gc; cin >> Gr >> Gc;
vector<vector<char>> a(r + 10, vector<char>(c + 10));
for (int i = 1; i <= r; ++i) {
for (int j = 1; j <= c; ++j) cin >> a[i][j];
}
auto in = [&](int x, int y) { return 1 <= x && x <= r && 1 <= y && y <= c; };
vector<DSU> R(r + 10, DSU(c + 10));
vector<DSU> C(c + 10, DSU(r + 10));
vector<vector<int>> f(r + 10, vector<int>(c + 10, 1'000'000'000));
deque<pair<int, int>> q;
q.push_back({Sr, Sc});
f[Sr][Sc] = 0;
while (q.size()) {
auto [x, y] = q.front(); q.pop_front();
auto add = [&](int nX, int nY, int w) {
if (f[nX][nY] > f[x][y] + w) {
f[nX][nY] = f[x][y] + w;
if (w) q.push_back({nX, nY});
else q.push_front({nX, nY});
}
};
for (int t = 0; t < 4; ++t) {
int nX = x + dx[t], nY = y + dy[t];
if (!in(nX, nY) || a[nX][nY] == '#') continue;
add(nX, nY, 0);
}
{ //add a fricking regtangle
int stX = max(1, x - n + 1), edX = min(r, x + n - 1);
int stY = max(1, y - n), edY = min(c, y + n);
for (int h = stX; h <= edX; h = C[stY].root(h)) {
add(h, stY, 1);
for (int i = R[h].root(stY); i < edY; i = R[h].root(i)) {
R[h].add(R[h].root(i) + 1, R[h].root(i));
add(h, R[h].root(i), 1);
}
if (R[h].root(stY) - stY >= 2 * n + 1) C[stY].add(h + 1, h);
h += 1;
}
}
{ //add 2 fricking strips due to the rectangle is not the fucking square
int stX = max(1, x - n), edX = min(r, x + n);
int stY = max(1, y - n + 1), edY = min(c, y + n - 1);
for (int type = 0; type < 2; ++type) {
int h = (!type ? stX : edX);
add(h, stY, 1);
for (int i = R[h].root(stY); i < edY; i = R[h].root(i)) {
R[h].add(R[h].root(i) + 1, R[h].root(i));
add(h, R[h].root(i), 1);
}
if (R[h].root(stY) - stY >= 2 * n + 1) C[stY].add(h + 1, h);
}
}
}
cout << f[Gr][Gc] << "\n";
}
