#include <bits/stdc++.h>
#define all(a) a.begin(), a.end()
using namespace std;
typedef long long ll;
int dx4[] = {1, -1, 0, 0};
int dy4[] = {0, 0, 1, -1};
int dx8[] = {1, -1, 0, 0, 1, 1, -1, -1};
int dy8[] = {0, 0, 1, -1, -1, 1, -1, 1};
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
int r, c, n, sr, sc, gr, gc;
cin >> r >> c >> n >> sr >> sc >> gr >> gc;
vector<string> a(r + 1);
for (int i = 1; i <= r; i++) cin >> a[i], a[i] = "#" + a[i];
vector<vector<pair<int, int>>> dist(r + 1, vector<pair<int, int>>(c + 1, {1e9, 1e9}));
vector<vector<bool>> vis(r + 1, vector<bool>(c + 1));
priority_queue<array<ll, 4>> pq;
dist[sr][sc] = {0, n - 1};
pq.push({0, -(n - 1), sr, sc});
while (!pq.empty()) {
int x = pq.top()[2];
int y = pq.top()[3];
pq.pop();
if (vis[x][y]) continue;
vis[x][y] = 1;
for (int dir = 0; dir < 4; dir++) {
int newx = x + dx4[dir];
int newy = y + dy4[dir];
if (1 <= newx && newx <= r && 1 <= newy && newy <= c) {
if (a[newx][newy] == '.') {
pair<int, int> p = {dist[x][y].first, n - 1};
if (dist[newx][newy] > p) {
dist[newx][newy] = p;
pq.push({-p.first, -p.second, newx, newy});
}
}
pair<int, int> p = {dist[x][y].first + 1, 0};
if (dist[newx][newy] > p) {
dist[newx][newy] = p;
pq.push({-p.first, -p.second, newx, newy});
}
}
}
if (dist[x][y].second < n - 1) {
for (int dir = 0; dir < 8; dir++) {
int newx = x + dx8[dir];
int newy = y + dy8[dir];
if (1 <= newx && newx <= r && 1 <= newy && newy <= c) {
pair<int, int> p = {dist[x][y].first, dist[x][y].second + 1};
if (dist[newx][newy] > p) {
dist[newx][newy] = p;
pq.push({-p.first, -p.second, newx, newy});
}
}
}
}
}
cout << dist[gr][gc].first << "\n";
return 0;
}
