#include <bits/stdc++.h>
#ifdef LOCAL
#include "Debug.h"
#else
#define debug(...) 42
#endif
using namespace std;
const int DX[] = {-1, 0, 1, 0, -1, -1, 1, 1};
const int DY[] = {0, 1, 0, -1, -1, 1, -1, 1};
const int oo = 27081993;
int r, c;
string a[2525];
int isValid(int x, int y)
{
return 0 <= x && x < r && 0 <= y && y < c;
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
int n, sx, sy, tx, ty;
cin >> r >> c >> n;
cin >> sx >> sy >> tx >> ty;
sx--; sy--; tx--; ty--;
for (int i = 0; i < r; i++)
cin >> a[i];
vector<vector<int>> dist(r, vector<int>(c, oo));
vector<vector<int>> dist2(r, vector<int>(c, oo));
vector<vector<int>> dir(r, vector<int>(c, -1));
vector<vector<int>> step(r, vector<int>(c));
dist[sx][sy] = 0;
vector<pair<int, int>> q = {{sx, sy}};
for (int curDist = 0; !empty(q); curDist++)
{
for (int i = 0; i < size(q); i++)
{
auto [x, y] = q[i];
dist2[x][y] = step[x][y] = 0;
for (int j = 0; j < 4; j++)
{
int xx = x + DX[j], yy = y + DY[j];
if (isValid(xx, yy) && dist[xx][yy] == oo && a[xx][yy] == '.')
{
dist[xx][yy] = curDist;
q.push_back({xx, yy});
}
}
}
vector<pair<int, int>> nextQ;
for (int i = 0; i < size(q); i++)
{
auto [x, y] = q[i];
if (dist[x][y] == oo)
{
dist[x][y] = curDist + 1;
nextQ.push_back({x, y});
}
if (dist2[x][y] == n)
continue;
for (int j = 0; j < 8; j++)
{
int xx = x + DX[j], yy = y + DY[j];
if (isValid(xx, yy) && dist2[xx][yy] == oo)
{
if (j == dir[x][y]) step[xx][yy] = step[x][y] + 1;
else step[xx][yy] = 1;
// exclude 4 corners
if (dist2[x][y] == n - 1 && step[xx][yy] == n && j >= 4)
continue;
q.push_back({xx, yy});
dist2[xx][yy] = dist2[x][y] + 1;
dir[xx][yy] = j;
}
}
}
swap(q, nextQ);
}
cout << dist[tx][ty] << endl;
}
