#include <bits/stdc++.h>
using namespace std;
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
int R, C, N;
cin >> R >> C >> N;
int Sr, Sc, Gr, Gc;
cin >> Sr >> Sc >> Gr >> Gc;
Sr--; Sc--; Gr--; Gc--; // Convert to 0-indexed
vector<string> grid(R);
for (int i = 0; i < R; i++) {
cin >> grid[i];
}
// 0-1 BFS with distance tracking
vector<vector<int>> dist(R, vector<int>(C, INT_MAX));
vector<vector<bool>> processed(R, vector<bool>(C, false));
deque<pair<int, int>> dq;
dist[Sr][Sc] = 0;
dq.push_back({Sr, Sc});
while (!dq.empty()) {
auto [x, y] = dq.front();
dq.pop_front();
// Skip if already processed
if (processed[x][y]) continue;
processed[x][y] = true;
// Early termination if we reached the goal
if (x == Gr && y == Gc) {
break;
}
// Move to adjacent white cells (cost 0)
int dx[] = {-1, 1, 0, 0};
int dy[] = {0, 0, -1, 1};
for (int d = 0; d < 4; d++) {
int nx = x + dx[d];
int ny = y + dy[d];
if (nx >= 0 && nx < R && ny >= 0 && ny < C &&
grid[nx][ny] == '.' && dist[nx][ny] > dist[x][y]) {
dist[nx][ny] = dist[x][y];
dq.push_front({nx, ny}); // Cost 0, add to front
}
}
// Apply stamp (cost 1)
// Find all valid stamp positions that include (x, y)
int a_min = max(0, x - N + 1);
int a_max = min(R - N, x);
int b_min = max(0, y - N + 1);
int b_max = min(C - N, y);
for (int a = a_min; a <= a_max; a++) {
for (int b = b_min; b <= b_max; b++) {
// Stamp at (a, b) covers cells [a, a+N) × [b, b+N)
for (int i = a; i < min(R, a + N); i++) {
for (int j = b; j < min(C, b + N); j++) {
if (dist[i][j] > dist[x][y] + 1) {
dist[i][j] = dist[x][y] + 1;
dq.push_back({i, j}); // Cost 1, add to back
}
}
}
}
}
}
cout << dist[Gr][Gc] << endl;
return 0;
}
