#include <bits/stdc++.h>
// #define int int64_t
const int kMaxT = 6e6 + 5, kMaxN = 3e3 + 5;
const int kD4[][2] = {{0, 1}, {0, -1}, {1, 0}, {-1, 0}};
const int kD8[][2] = {{1, 1}, {1, -1}, {-1, 1}, {-1, -1}, {0, 1}, {0, -1}, {1, 0}, {-1, 0}};
int n, m, k;
int sx, sy, tx, ty;
std::vector<int> G[kMaxT];
std::string s[kMaxN];
void dijkstra() {
std::vector<std::vector<std::pair<int, int>>> dis(n + 1, std::vector<std::pair<int, int>>(m + 1));
std::vector<std::vector<bool>> vis(n + 1, std::vector<bool>(m + 1));
std::priority_queue<std::tuple<int, int, int, int>> q;
for (int i = 1; i <= n; ++i)
for (int j = 1; j <= m; ++j)
dis[i][j] = {1e9, 1e9};
dis[sx][sy] = {0, k - 1};
q.emplace(0, -(k - 1), sx, sy);
for (; !q.empty();) {
auto [d, w, x, y] = q.top();
q.pop();
if (vis[x][y]) continue;
vis[x][y] = 1;
for (auto [dx, dy] : kD4) {
int tx = x + dx, ty = y + dy;
if (tx < 1 || tx > n || ty < 1 || ty > m) continue;
if (s[tx][ty] == '.') {
std::pair<int, int> p = {dis[x][y].first, k - 1};
if (dis[tx][ty] > p) {
dis[tx][ty] = p;
q.emplace(-p.first, -p.second, tx, ty);
}
}
std::pair<int, int> p = {dis[x][y].first + 1, 0};
if (dis[tx][ty] > p) {
dis[tx][ty] = p;
q.emplace(-p.first, -p.second, tx, ty);
}
}
if (dis[x][y].second < k - 1) {
for (auto [dx, dy] : kD8) {
int tx = x + dx, ty = y + dy;
if (tx < 1 || tx > n || ty < 1 || ty > m) continue;
std::pair<int, int> p = {dis[x][y].first, dis[x][y].second + 1};
if (dis[tx][ty] > p) {
dis[tx][ty] = p;
q.emplace(-p.first, -p.second, tx, ty);
}
}
}
}
std::cout << dis[tx][ty].first << '\n';
}
void dickdreamer() {
std::cin >> n >> m >> k >> sx >> sy >> tx >> ty;
for (int i = 1; i <= n; ++i) {
std::cin >> s[i];
s[i] = " " + s[i];
}
dijkstra();
}
int32_t main() {
#ifdef ORZXKR
freopen("in.txt", "r", stdin);
freopen("out.txt", "w", stdout);
#endif
std::ios::sync_with_stdio(0), std::cin.tie(0), std::cout.tie(0);
int T = 1;
// std::cin >> T;
while (T--) dickdreamer();
// std::cerr << 1.0 * clock() / CLOCKS_PER_SEC << "s\n";
return 0;
}
