#include <bits/stdc++.h>
using namespace std;
#define forsn(i, s, n) for (int i = int(s); i < int(n); i++)
#define forn(i, n) forsn(i, 0, n)
#define dforsn(i, s, n) for (int i = int(n) - 1; i >= int(s); i--)
#define dforn(i, n) dforsn(i, 0, n)
#define qforn(i, n) for (i = 0; i < n; i++)
using vi = vector<int>;
using ii = pair<int, int>;
using vii = vector<ii>;
using ll = long long;
using ld = long double;
using vll = vector<ll>;
using vb = vector<bool>;
using pll = pair<ll, ll>;
#define sz(x) int(x.size())
#define all(x) begin(x), end(x)
#define pb push_back
#define eb emplace_back
#define ef emplace_front
#define fst first
#define snd second
const int dx[] = {0, 0, 1, -1, 1, -1, 1, -1};
const int dy[] = {1, -1, 0, 0, 1, -1, -1, 1};
const int INF = 1e9;
int main() {
ios::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
int n, m, k;
cin >> n >> m >> k;
int sx, sy, tx, ty;
cin >> sx >> sy >> tx >> ty;
--sx, --sy, --tx, --ty;
vector<string> grid(n);
forn(i, n) cin >> grid[i];
vector<vii> dist(n, vii(m, make_pair(INF, INF)));
deque<pair<ii, ii>> dq;
dq.eb(dist[sx][sy] = make_pair(0, k - 1), make_pair(sx, sy));
while (!dq.empty()) {
auto [d, u] = dq.front();
dq.pop_front();
auto [x, y] = u;
if (dist[x][y] != d) continue;
if (d.snd + 1 < k) {
forn(i, 8) {
int nx = x + dx[i];
int ny = y + dy[i];
if (!(0 <= nx && nx < n)) continue;
if (!(0 <= ny && ny < m)) continue;
if (dist[nx][ny] > make_pair(d.fst, d.snd + 1)) {
dq.eb(dist[nx][ny] = make_pair(d.fst, d.snd + 1), make_pair(nx, ny));
}
}
} else {
forn(i, 4) {
int nx = x + dx[i];
int ny = y + dy[i];
if (!(0 <= nx && nx < n)) continue;
if (!(0 <= ny && ny < m)) continue;
if (grid[nx][ny] == '#') {
if (dist[nx][ny] > make_pair(d.fst + 1, 0)) {
dq.eb(dist[nx][ny] = make_pair(d.fst + 1, 0), make_pair(nx, ny));
}
} else {
if (dist[nx][ny] > d) {
dq.ef(dist[nx][ny] = d, make_pair(nx, ny));
}
}
}
}
}
cout << dist[tx][ty].fst << "\n";
return 0;
}
