#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using pii = pair<int, int>;
using pll = pair<long long, long long>;
using ull = unsigned long long;
#define X first
#define Y second
#define SZ(x) int(x.size())
#define all(x) x.begin(), x.end()
#define mins(a,b) (a = min(a,b))
#define maxs(a,b) (a = max(a,b))
#define pb push_back
#define Mp make_pair
#define lc id<<1
#define rc lc|1
#define mid ((l+r)/2)
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
const ll INF = 1e9 + 23;
const ll MOD = 1e9 + 7;
const int MXN = 2e5 + 23;
const int LOG = 23;
int R, C, N, sr, sc, er, ec;
vector<vector<char>> a;
int dx4[4] = {-1, 0, 1, 0};
int dy4[4] = {0, 1, 0, -1};
int dx8[8] = {-1, -1, 0, 1, 1, 1, 0, -1};
int dy8[8] = {0, 1, 1, 1, 0, -1, -1, -1};
vector<vector<int>> dis, dis4, dis8;
vector<pii> V, U;
int D;
bool in(int x, int y) {
return 0<=x&&x<R && 0<=y&&y<C;
}
void BFS() {
queue<pii> q;
for(auto p : V) {
dis[p.X][p.Y] = D;
q.push(p);
}
while(SZ(q)) {
int x = q.front().X, y = q.front().Y;
q.pop();
for(int d=0; d<4; d++) {
int xx = x+dx4[d], yy = y+dy4[d];
if(in(xx, yy) && a[xx][yy]=='.' && dis[xx][yy] == INF) {
dis[xx][yy] = D;
V.pb(Mp(xx, yy));
q.push(Mp(xx, yy));
}
}
}
}
void BFS8() {
queue<pii> q;
for(auto p : V) {
dis8[p.X][p.Y] = 0;
U.pb(p);
q.push(p);
}
while(SZ(q)) {
int x = q.front().X, y = q.front().Y;
q.pop();
if(dis8[x][y] == N) continue;
for(int d=0; d<8; d++) {
int xx = x+dx8[d], yy = y+dy8[d];
if(in(xx, yy) && dis[xx][yy] == INF && dis8[x][y]+1<dis8[xx][yy]) {
dis8[xx][yy] = dis8[x][y]+1;
U.pb(Mp(xx, yy));
q.push(Mp(xx, yy));
}
}
}
}
void BFS4() {
queue<pii> q;
for(auto p : V) {
dis4[p.X][p.Y] = 0;
q.push(p);
}
while(SZ(q)) {
int x = q.front().X, y = q.front().Y;
q.pop();
for(int d=0; d<4; d++) {
int xx = x+dx4[d], yy = y+dy4[d];
if(in(xx, yy) && dis[xx][yy] == INF && dis8[xx][yy] != INF && dis4[x][y]+1<dis4[xx][yy]) {
dis4[xx][yy] = dis4[x][y]+1;
q.push(Mp(xx, yy));
}
}
}
}
void Upd() {
V.clear();
for(auto [x, y] : U) {
if(dis[x][y] == INF && (dis8[x][y]<N || dis4[x][y]<N+N))
V.pb(Mp(x, y));
dis8[x][y] = dis4[x][y] = INF;
}
U.clear();
}
void SP() {
V = {{sr, sc}};
while(1) {
BFS();
BFS8();
BFS4();
Upd();
if(V.empty()) break;
D++;
}
}
void Main() {
cin >> R >> C >> N;
cin >> sr >> sc >> er >> ec; sr--; sc--; er--; ec--;
a = vector<vector<char>>(R, vector<char>(C));
dis = vector<vector<int>>(R, vector<int>(C, INF));
dis4 = vector<vector<int>>(R, vector<int>(C, INF));
dis8 = vector<vector<int>>(R, vector<int>(C, INF));
for(int r=0; r<R; r++)
for(int c=0; c<C; c++)
cin >> a[r][c];
SP();
cout << dis[er][ec] << '\n';
}
int32_t main() {
cin.tie(0); cout.tie(0); ios_base::sync_with_stdio(0);
int T = 1;
// cin >> T;
while(T--) Main();
return 0;
}
