#include <bits/stdc++.h>
using namespace std;
struct Cell {
int r, c;
};
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
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-based
vector<string> grid(R);
for (int i = 0; i < R; i++) cin >> grid[i];
// Distance array: min stamp count to reach each cell
vector<int> dist(R * C, INT_MAX);
deque<int> dq;
auto idx = [&](int r, int c) { return r * C + c; };
// Starting point
dist[idx(Sr, Sc)] = 0;
dq.push_back(idx(Sr, Sc));
// For each cell, precompute stamp top-left range that can paint it
// Stamp top-left corner a,b must satisfy:
// a in [r - N + 1, r] and 0 <= a <= R - N
// b in [c - N + 1, c] and 0 <= b <= C - N
vector<vector<pair<int,int>>> stampCover(R * C);
for (int r = 0; r < R; r++) {
int amin = max(0, r - N + 1);
int amax = min(r, R - N);
for (int c = 0; c < C; c++) {
int bmin = max(0, c - N + 1);
int bmax = min(c, C - N);
auto &vec = stampCover[idx(r, c)];
for (int a = amin; a <= amax; a++) {
for (int b = bmin; b <= bmax; b++) {
vec.push_back({a, b});
}
}
}
}
// For each stamp position (a,b), precompute cells it covers
int totalStamps = (R - N + 1) * (C - N + 1);
vector<vector<int>> stampCells(totalStamps);
auto stampIdx = [&](int a, int b) { return a * (C - N + 1) + b; };
for (int a = 0; a <= R - N; a++) {
for (int b = 0; b <= C - N; b++) {
auto &vec = stampCells[stampIdx(a, b)];
vec.reserve(N * N);
for (int dr = 0; dr < N; dr++) {
for (int dc = 0; dc < N; dc++) {
int rr = a + dr, cc = b + dc;
vec.push_back(idx(rr, cc));
}
}
}
}
vector<bool> usedStamp(totalStamps, false);
// 0-1 BFS
while (!dq.empty()) {
int cur = dq.front();
dq.pop_front();
int r = cur / C, c = cur % C;
if (r == Gr && c == Gc) {
cout << dist[cur] << "\n";
return 0;
}
// Move to adjacent white cells with cost 0
static int dr[4] = {-1, 1, 0, 0};
static int dc[4] = {0, 0, -1, 1};
for (int k = 0; k < 4; k++) {
int nr = r + dr[k], nc = c + dc[k];
if (nr < 0 || nr >= R || nc < 0 || nc >= C) continue;
if (grid[nr][nc] == '.' && dist[idx(nr, nc)] > dist[cur]) {
dist[idx(nr, nc)] = dist[cur];
dq.push_front(idx(nr, nc));
}
}
// Use stamps to paint black cells (cost +1)
for (auto [a, b] : stampCover[cur]) {
int si = stampIdx(a, b);
if (usedStamp[si]) continue;
usedStamp[si] = true;
for (int cell : stampCells[si]) {
if (dist[cell] > dist[cur] + 1) {
dist[cell] = dist[cur] + 1;
dq.push_back(cell);
}
}
}
}
return 0;
}
