// File maze.cpp created on 29.09.2025 at 10:19:41
#include <bits/stdc++.h>
using i64 = long long;
#ifdef DEBUG
#include "/home/ahmetalp/Desktop/Workplace/debug.h"
#else
#define debug(...) void(23)
#endif
constexpr int dx[] = {0, +1, 0, -1};
constexpr int dy[] = {+1, 0, -1, 0};
template<typename T>
bool chmin(T& a, T b) {
if (a > b) {
a = b;
return true;
}
return false;
}
struct fenwick {
int n, m;
std::vector<std::vector<int>> tree;
fenwick(int n_, int m_) : n(n_), m(m_), tree(n + 1, std::vector<int>(m + 1)) {}
void modify(int px, int py, int x) {
for (int a = px + 1; a <= n; a += a & -a) {
for (int b = py + 1; b <= m; b += b & -b) {
tree[a][b] += x;
}
}
}
void modify(int a, int b, int c, int d, int x) {
a = std::max(a, 0);
b = std::max(b, 0);
c = std::min(c, n - 1);
d = std::min(d, m - 1);
debug(a, b, c, d);
modify(a, b, +x);
modify(a, d + 1, -x);
modify(c + 1, b, -x);
modify(c + 1, d + 1, +x);
}
int get(int px, int py) {
int res = 0;
for (int a = px + 1; a; a -= a & -a) {
for (int b = py + 1; b; b -= b & -b) {
res += tree[a][b];
}
}
return res;
}
};
int main() {
std::ios::sync_with_stdio(false);
std::cin.tie(nullptr);
int R, C, N;
std::cin >> R >> C >> N;
auto in = [&](int x, int y) -> bool {
return 0 <= x && x < R && 0 <= y && y < C;
};
int SX, SY, GX, GY;
std::cin >> SX >> SY >> GX >> GY;
--SX, --SY, --GX, --GY;
std::vector<std::string> A(R);
for (int i = 0; i < R; ++i) {
std::cin >> A[i];
}
std::vector<std::vector<int>> vis(R, std::vector<int>(C));
std::vector<std::vector<int>> dis(R, std::vector<int>(C, R * C));
std::vector<std::pair<int, int>> deq;
dis[SX][SY] = 0;
deq.emplace_back(SX, SY);
for (int diss = 0; ; ++diss) {
fenwick fen(R, C);
std::vector<std::pair<int, int>> ndeq;
for (int i = 0; i < int(deq.size()); ++i) {
auto[x, y] = deq[i];
if (dis[x][y] != diss) {
continue;
}
debug(x, y, diss);
for (int d = 0; d < 4; ++d) {
int nx = x + dx[d];
int ny = y + dy[d];
if (in(nx, ny)) {
if (A[nx][ny] == '.') {
if (chmin(dis[nx][ny], dis[x][y])) {
deq.emplace_back(nx, ny);
}
}
}
}
fen.modify(x - N, y - N, x + N, y + N, +1);
if (in(x - N, y - N)) {
fen.modify(x - N, y - N, x - N, y - N, -1);
}
if (in(x - N, y + N)) {
fen.modify(x - N, y + N, x - N, y + N, -1);
}
if (in(x + N, y - N)) {
fen.modify(x + N, y - N, x + N, y - N, -1);
}
if (in(x + N, y + N)) {
fen.modify(x + N, y + N, x + N, y + N, -1);
}
// for (int DX = -N; DX <= N; ++DX) {
// for (int DY = -N; DY <= N; ++DY) {
// if (std::abs(DX) == N && std::abs(DY) == N) {
// continue;
// }
// int X = x + DX;
// int Y = y + DY;
// if (0 <= X && X < R && 0 <= Y && Y < C) {
// if (chmin(dis[X][Y], dis[x][y] + 1)) {
// ndeq.emplace_back(X, Y);
// }
// }
// }
// }
}
#ifdef DEBUG
for (int i = 0; i < R; ++i) {
for (int j = 0; j < C; ++j) {
std::cerr << fen.get(i, j) << " \n"[j == C - 1];
}
}
#endif
for (int i = 0; i < R; ++i) {
for (int j = 0; j < C; ++j) {
if (fen.get(i, j) > 0 && dis[i][j] > diss + 1) {
dis[i][j] = diss + 1;
ndeq.emplace_back(i, j);
}
}
}
if (ndeq.empty()) {
break;
}
deq = std::move(ndeq);
}
std::cout << dis[GX][GY] << '\n';
return 0;
}
