#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int r, c, s1, s2, e1, e2, n;
struct S {
int x, y;
S() { x = y = 0; }
S(int x, int y) {
this->x = x;
this->y = y;
}
vector<S> nxt() {
vector<S> nx;
if (x > 0)
nx.push_back({x - 1, y});
if (x + 1 < r)
nx.push_back({x + 1, y});
if (y > 0)
nx.push_back({x, y - 1});
if (y + 1 < c)
nx.push_back({x, y + 1});
return nx;
}
vector<S> rnxt() {
vector<S> nx = nxt();
if (x > 0 && y > 0)
nx.push_back({x - 1, y - 1});
if (x > 0 && y + 1 < c)
nx.push_back({x - 1, y + 1});
if (x + 1 < r && y > 0)
nx.push_back({x + 1, y - 1});
if (x + 1 < r && y + 1 < c)
nx.push_back({x + 1, y + 1});
return nx;
}
};
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
cin >> r >> c >> n >> s1 >> s2 >> e1 >> e2, --s1, --s2, --e1, --e2;
vector g(r, vector<int>(c));
for (int i = 0; i < r; ++i) {
for (int j = 0; j < c; ++j) {
char t;
cin >> t;
g[i][j] = (t != '#');
}
}
const int inf = (1 << 30);
queue<S> q1, q2;
S N = {-1, -1};
q2.push(N);
q1.push({s1, s2});
int D = 0;
vector dist(r, vector<int>(c, inf));
dist[s1][s2] = 0;
while (q1.size() || q2.size() > 1) {
while (q1.size()) {
S cur = q1.front();
q1.pop();
auto nx = cur.nxt();
for (auto [x, y] : nx) {
if (g[x][y]) {
if (dist[x][y] == inf) {
dist[x][y] = dist[cur.x][cur.y];
q1.push({x, y});
}
} else {
if (dist[x][y] == inf) {
q2.push({x, y});
dist[x][y] = dist[cur.x][cur.y] + 1;
}
}
}
}
while (q2.size() > 1) {
if (D == n) {
D = 0;
while (q2.size() && ~q2.front().x) {
q1.push(q2.front());
q2.pop();
}
break;
}
S cur = q2.front();
q2.pop();
if (!~cur.x) {
D++;
q2.push(N);
continue;
}
auto nx = cur.rnxt();
for (auto [x, y] : nx) {
if (dist[x][y] == inf) {
dist[x][y] = dist[cur.x][cur.y];
q2.push({x, y});
}
}
}
}
cout << dist[e1][e2];
return 0;
}
