#include<bits/stdc++.h>
#define fi first
#define se second
#define endl "\n"
#define ii pair<int, int>
using namespace std;
vector<vector<int> > a, f, mark, row, col;
int mx[4] = {0, 0, -1, 1};
int my[4] = {1, -1, 0, 0};
int findr(int i, int j) {
return !mark[i][j] ? i : row[i][j] = findr(row[i][j], j);
}
int findc(int i, int j) {
return !mark[i][j] ? j : col[i][j] = findc(i, col[i][j]);
}
int main() {
#define task ""
cin.tie(0) -> sync_with_stdio(0);
if (fopen ("task.inp", "r")) {
freopen ("task.inp", "r", stdin);
// freopen ("task.out", "w", stdout);
}
if (fopen (task".inp", "r")) {
freopen (task".inp", "r", stdin);
freopen (task".out", "w", stdout);
}
int r, c, n; cin >> r >> c >> n;
a = vector<vector<int> > (r + 2, vector<int> (c + 2));
f = vector<vector<int> > (r + 2, vector<int> (c + 2));
mark = vector<vector<int> > (r + 2, vector<int> (c + 2));
row = vector<vector<int> > (r + 2, vector<int> (c + 2));
col = vector<vector<int> > (r + 2, vector<int> (c + 2));
int sr, sc, gr, gc; cin >> sr >> sc >> gr >> gc;
for(int i = 1; i <= r; i++) for(int j = 1; j <= c; j++) {
char c; cin >> c;
if (c == '.') a[i][j] = 0;
else a[i][j] = 1;
f[i][j] = 1e9;
row[i][j] = i + 1;
col[i][j] = j + 1;
}
deque<tuple<int, int, int> > q;
f[sr][sc] = 0;
q.push_back({0, sr, sc});
while (!q.empty()) {
int cost, x, y; tie(cost, x, y) = q.front(); q.pop_front();
if (cost != f[x][y]) continue;
int d1 = abs(gr - x), d2 = abs(gc - y);
if (d1 > d2) swap(d1, d2);
if (d1 < n && d2 <= n && f[gr][gc] > f[x][y] + 1) {
f[gr][gc] = f[x][y] + 1;
q.push_back({f[gr][gc], gr, gc});
}
for(int k = 0; k < 4; k++) {
int xx = x + mx[k], yy = y + my[k];
if (xx < 1 || xx > r || yy < 1 || yy > c || a[xx][yy]) continue;
if (f[xx][yy] > f[x][y]) {
f[xx][yy] = f[x][y];
q.push_front({f[xx][yy], xx, yy});
}
}
int i, j;
if (x > n) {
i = x - n;
j = max(1, y - n + 1);
for(j = findc(i, j); j <= min(c, y + n - 1); j = findc(i, j)) {
if (f[i][j] > f[x][y] + 1) {
f[i][j] = f[x][y] + 1;
q.push_back({f[i][j], i, j});
}
mark[i][j] = 1;
}
}
if (x + n <= r) {
i = x + n;
j = max(1, y - n + 1);
for(j = findc(i, j); j <= min(c, y + n - 1); j = findc(i, j)) {
if (f[i][j] > f[x][y] + 1) {
f[i][j] = f[x][y] + 1;
q.push_back({f[i][j], i, j});
}
mark[i][j] = 1;
}
}
if (y > n) {
j = y - n;
i = max(1, x - n + 1);
for(i = findr(i, j); i <= min(r, x + n - 1); i = findr(i, j)) {
if (f[i][j] > f[x][y] + 1) {
f[i][j] = f[x][y] + 1;
q.push_back({f[i][j], i, j});
}
mark[i][j] = 1;
}
}
if (y + n <= c) {
j = y + n;
i = max(1, x - n + 1);
for(i = findr(i, j); i <= min(r, x + n - 1); i = findr(i, j)) {
if (f[i][j] > f[x][y] + 1) {
f[i][j] = f[x][y] + 1;
q.push_back({f[i][j], i, j});
}
mark[i][j] = 1;
}
}
}
cout << f[gr][gc];
}
