#include <bits/stdc++.h>
using namespace std;
using ld = long double;
using ll = long long;
const int INF = 1e9, MOD = 1e9 + 7;
void solve();
signed main() {
#ifdef LOCAL
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
#endif
ios::sync_with_stdio(false);
cin.tie(0);
int q = 1;
while (q--) {
solve();
}
}
vector<pair<int, int>> cord = {{0, 1}, {1, 0}, {0, -1}, {-1, 0}};
void solve() {
int r, c, n;
cin >> r >> c >> n;
int sr, sc, gr, gc;
cin >> sr >> sc >> gr >> gc;
sr--, sc--, gr--, gc--;
vector<vector<char>> a(r, vector<char>(c));
for (int i = 0; i < r; i++) {
for (int j = 0; j < c; j++) {
cin >> a[i][j];
}
}
if (r > c) {
swap(r, c);
swap(sr, sc);
swap(gr, gc);
vector<vector<char>> nw(r, vector<char>(c));
for (int i = 0; i < r; i++) {
for (int j = 0; j < c; j++) {
nw[i][j] = a[j][i];
}
}
a = nw;
}
if (n >= r) {
queue<pair<int, int>> bfs;
bfs.emplace(sr, sc);
vector<vector<int>> used(r, vector<int>(c));
used[sr][sc] = 1;
int mn = sc, mx = sc;
while (!empty(bfs)) {
auto [i, j] = bfs.front();
bfs.pop();
mn = min(mn, j); mx = max(mx, j);
for (auto [fx, fy] : cord) {
int x = i + fx, y = j + fy;
if (x < 0 || y < 0 || x == r || y == c || a[x][y] == '#') {
continue;
}
if (used[x][y]) {
continue;
}
used[x][y] = 1;
bfs.emplace(x, y);
}
}
int col = 0;
int lf = sc + 1, rf = sc - 1;
while (!used[gr][gc]) {
int nwl = max(0, mn - n), nwr = min(c - 1, mx + n);
for (int i = 0; i < r; i++) {
for (int j = nwl; j < lf; j++) {
used[i][j] = 1;
}
for (int j = rf + 1; j <= nwr; j++) {
used[i][j] = 1;
}
}
col++;
lf = nwl;
rf = nwr;
for (int i = 0; i < r; i++) {
bfs.emplace(i, lf);
bfs.emplace(i, rf);
}
while (!empty(bfs)) {
auto [i, j] = bfs.front();
bfs.pop();
mn = min(mn, j); mx = max(mx, j);
for (auto [fx, fy] : cord) {
int x = i + fx, y = j + fy;
if (x < 0 || y < 0 || x == r || y == c || a[x][y] == '#') {
continue;
}
if (used[x][y]) {
continue;
}
used[x][y] = 1;
bfs.emplace(x, y);
}
}
}
cout << col << "\n";
return;
}
vector<vector<int>> used(r, vector<int>(c));
vector<vector<int>> nxt(r, vector<int>(c + 1));
for (int i = 0; i < r; i++) {
for (int j = 0; j <= c; j++) {
nxt[i][j] = j;
}
}
auto get_nxt = [&](auto& self, int i, int j) -> int {
return nxt[i][j] == j ? j : nxt[i][j] = self(self, i, nxt[i][j]);
};
int col = 0;
queue<pair<int, int>> bfs;
bfs.emplace(sr, sc);
used[sr][sc] = 1;
nxt[sr][sc] = sc + 1;
vector<pair<int, int>> elems;
vector<vector<pair<int, int>>> segs(r);
while (!bfs.empty()) {
auto [i, j] = bfs.front();
bfs.pop();
elems.emplace_back(i, j);
for (auto [fx, fy] : cord) {
int x = i + fx, y = j + fy;
if (x < 0 || y < 0 || x == r || y == c || a[x][y] == '#') {
continue;
}
if (used[x][y]) {
continue;
}
used[x][y] = 1;
nxt[x][y] = y + 1;
bfs.emplace(x, y);
}
}
while (!used[gr][gc]) {
vector<int> id;
for (auto [x, y] : elems) {
for (int i = max(0, x - n); i <= min(r - 1, x + n); i++) {
id.push_back(i);
int lf = max(0, y - n);
int rf = min(c - 1, y + n);
if (abs(x - i) == n) {
lf = max(0, y - n + 1);
rf = min(c - 1, y + n - 1);
}
if (lf <= rf) {
segs[i].emplace_back(lf, rf);
}
}
}
for (auto i : id) {
if (segs[i].empty()) continue;
sort(segs[i].begin(), segs[i].end());
int cur_l = segs[i][0].first;
int cur_r = segs[i][0].second;
for (size_t k = 1; k < segs[i].size(); k++) {
if (segs[i][k].first <= cur_r) {
cur_r = max(cur_r, segs[i][k].second);
} else {
int cur = get_nxt(get_nxt, i, cur_l);
while (cur <= cur_r) {
used[i][cur] = 1;
bfs.emplace(i, cur);
nxt[i][cur] = cur + 1;
cur = get_nxt(get_nxt, i, cur);
}
cur_l = segs[i][k].first;
cur_r = segs[i][k].second;
}
}
int cur = get_nxt(get_nxt, i, cur_l);
while (cur <= cur_r) {
used[i][cur] = 1;
bfs.emplace(i, cur);
nxt[i][cur] = cur + 1;
cur = get_nxt(get_nxt, i, cur);
}
segs[i].clear();
}
vector<pair<int, int>> nw;
while (!bfs.empty()) {
auto [i, j] = bfs.front();
bfs.pop();
nw.emplace_back(i, j);
for (auto [fx, fy] : cord) {
int x = i + fx, y = j + fy;
if (x < 0 || y < 0 || x == r || y == c || a[x][y] == '#') {
continue;
}
if (used[x][y]) {
continue;
}
used[x][y] = 1;
nxt[x][y] = y + 1;
bfs.emplace(x, y);
}
}
elems = move(nw);
col++;
}
cout << col << "\n";
}
