#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define vi vector<ll>
#define vvi vector<vector<ll>>
#define vs vector<string>
#define vc vector<char>
#define vb vector<bool>
#define vp vector<pair<ll, ll>>
#define pp pair<ll, ll>
#define qi queue<ll>
#define qp queue<pp>
#define pqi priority_queue<ll>
#define pqp priority_queue<pp>
#define mi map<ll, ll>
#define mpi map<pp, ll>
#define mip map<ll, pp>
#define mpp map<pp, pp>
#define mb map<ll, bool>
#define si set<ll>
#define sp set<pp>
#define mod 1000000007
#define rep(a, b) for(int a = 0; a < (b); a++)
#define inf 100000000111111111
int main()
{
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
int r, s, n;
qi q;
cin >> r >> s >> n;
int startr, starts, endr, ends;
cin >> startr >> starts >> endr >> ends;
startr--; starts--; ends--; endr--;
vvi table(r), dist(r), distbfs(r);
rep(i, r) {
table[i].resize(s);
dist[i].resize(s);
distbfs[i].resize(s);
rep(j, s) {
char ch;
cin >> ch;
if (ch == '.') {
table[i][j] = 0;
}
else {
table[i][j] = -1;
}
dist[i][j] = inf;
distbfs[i][j] = 0;
}
}
vp sousedi = { {0, 1}, {0, -1}, {1, 0}, {-1, 0} };
vp sousedi2 = { {0, 1}, {0, -1}, {1, 0}, {-1, 0}, {1, 1}, {-1, -1}, {1, -1}, {-1, 1} };
vp prevdist;
qp q1;
q1.push({startr, starts});
while (!q1.empty()) {
pp x = q1.front();
q1.pop();
dist[x.first][x.second] = 0;
prevdist.push_back(x);
for (pp i : sousedi) {
ll a = x.first + i.first;
ll b = x.second + i.second;
if (a < r && a >= 0 && b < s && b >= 0) {
if (table[a][b] == 0 && dist[a][b] == inf) {
q1.push({ a, b });
dist[a][b] = 0;
}
}
}
}
ll pomoc = 0;
while (dist[endr][ends] == inf) {
/*rep(i, r) {
rep(j, s) {
cout << dist[i][j] << " ";
}
cout << endl;
}*/
pomoc++;
qp q2;
for (int i = 0; i < prevdist.size(); i++) {
for (pp j : sousedi) {
ll a = prevdist[i].first + j.first;
ll b = prevdist[i].second + j.second;
if (a < r && a >= 0 && b < s && b >= 0) {
if (dist[a][b] == inf && distbfs[a][b] != n) {
q2.push({ a, b });
distbfs[a][b] = n;
}
}
}
}
/*rep(i, r) {
rep(j, s) {
cout << distbfs[i][j] << " ";
}
cout << endl;
}*/
//cout << endl;
prevdist.clear();
while (!q2.empty()) {
pp x = q2.front();
prevdist.push_back(x);
q2.pop();
dist[x.first][x.second] = pomoc;
if (distbfs[x.first][x.second] <= 1) {
continue;
}
ll xd = distbfs[x.first][x.second];
for (pp i : sousedi2) {
ll a = x.first + i.first;
ll b = x.second + i.second;
if (a < r && a >= 0 && b < s && b >= 0) {
if (dist[a][b] == inf && distbfs[a][b] == 0) {
dist[a][b] = pomoc;
q2.push({ a, b });
distbfs[a][b] = xd - 1;
}
}
}
}
qp q3;
rep(i, prevdist.size()) {
q3.push(prevdist[i]);
}
while (!q3.empty()) {
pp x = q3.front();
q3.pop();
for (pp i : sousedi) {
ll a = x.first + i.first;
ll b = x.second + i.second;
if (a < r && a >= 0 && b < s && b >= 0) {
if (dist[a][b] == inf && table[a][b] == 0) {
q3.push({ a, b });
dist[a][b] = pomoc;
prevdist.push_back({ a, b });
}
}
}
}
}
cout << dist[endr][ends] << endl;
}
