#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define pf push_front
#define mp make_pair
#define fi first
#define se second
#define int long long
#define all(x) (x).begin(), (x).end()
typedef long double ld;
typedef long long ll;
typedef pair<ll,ll> pll;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<bool> vb;
typedef vector<vector<int>> vvi;
typedef vector<vector<bool>> vvb;
typedef vector<vector<ll>> vvll;
typedef vector<string> vs;
typedef vector<vector<string>> vvs;
typedef vector<char> vc;
typedef vector<vector<char>> vvc;
typedef map<int, int> mii;
typedef unordered_map<int, int> umii;
const int mod = 1e9 + 7;
const int inf = INTMAX_MAX;
const bool tc = false;
int r, c, k;
vvi g;
vector<pii> dir = {
{0, 1},
{0, -1},
{-1, 0},
{1, 0}
};
bool valid(int r1, int c1) {
if (r1 < 0) return false;
if (r1 >= r) return false;
if (c1 < 0) return false;
if (c1 >= c) return false;
return true;
}
inline void solve() {
cin >> r >> c >> k;
pii s, e; cin >> s.fi >> s.se; cin >> e.fi >> e.se;
s.fi--; s.se--; e.fi--; e.se--;
g.assign(r, vi(c));
for (int i = 0; i < r; i++) {
for (int j = 0; j < c; j++) {
char x; cin >> x;
g[i][j] = (x == '#');
}
}
set<pair<pii, int>> st; st.insert({s, 0});
vvi dist(r, vi(c, 1e18));
while (st.size()) {
auto cur = *st.begin();
st.erase(st.begin());
// cout << cur.fi.se + 1 << " " << cur.fi.fi + 1 << "\n";
for (auto &p : dir) {
pii ng = cur.fi;
ng.fi += p.fi; ng.se += p.se;
if (!valid(ng.fi, ng.se)) continue;
if (g[ng.fi][ng.se]) continue;
if (cur.se > dist[ng.fi][ng.se]) {
st.erase({ng, dist[ng.fi][ng.se]});
dist[ng.fi][ng.se] = cur.se;
st.insert({ng, cur.se});
}
}
pii node = cur.fi;
for (int r2 = 0; r2 < r; r2++) {
for (int c2 = 0; c2 < c; c2++) {
int dy = abs(node.fi - r2), dx = abs(node.se - c2);
if (dx > k + 1 || dy > k + 1 || ((dx==k)&&(dy==k))) continue;
if (cur.se + 1 > dist[r2][c2]) continue;
st.erase({{r2, c2}, dist[r2][c2]});
dist[r2][c2] = cur.se + 1;
st.insert({{r2, c2}, dist[r2][c2]});
}
}
}
cout << dist[e.fi][e.se] << '\n';
}
void setIO(string s) {
freopen((s + ".in").c_str(), "r", stdin);
freopen((s + ".out").c_str(), "w", stdout);
}
signed main() {
ios::sync_with_stdio(false);
cout.tie(0);
cin.tie(0);
//setIO();
int t = 1;
if (tc) {
cin >> t;
}
while (t--) {
solve();
}
}
