#include <bits/stdc++.h>
#define pb push_back
using namespace std;
constexpr static int MAX_R = 2500;
int r, c, n;
vector<int> min_dist[MAX_R];
vector<vector<array<int, 2>>> steps;
vector<bool> white[MAX_R];
vector<bool> visited[MAX_R];
vector<bool> seen[MAX_R];
void clean_dfs(int x, int y, int step);
void clean_check(int x, int y, int step)
{
if (c > x && x >= 0 && r > y && y >= 0 && !visited[y][x] && white[y][x])
clean_dfs(x, y, step);
}
void clean_dfs(int x, int y, int step)
{
visited[y][x] = true;
min_dist[y][x] = step;
if (!seen[y][x])
steps[step].pb({x, y});
clean_check(x-1, y, step);
clean_check(x+1, y, step);
clean_check(x, y-1, step);
clean_check(x, y+1, step);
}
vector<int> bvert[MAX_R];
vector<int> bhrz[MAX_R];
void bfs(int step)
{
queue<array<int, 2>> vq, hq;
for (array<int, 2> pos : steps[step])
vq.push(pos);
while (vq.size())
{
auto [x, y] = vq.front();
vq.pop();
if (min_dist[y][x] == step)
bvert[y][x] = 0;
for (int dy = -1; dy <= 1; dy+=2)
{
if (r > y+dy && y+dy >= 0 && !visited[y+dy][x] && !seen[y+dy][x])
{
seen[y+dy][x] = true;
min_dist[y+dy][x] = step + 1;
steps[step+1].pb({x, y+dy});
bvert[y+dy][x] = bvert[y][x]+1;
if (bvert[y+dy][x] < n)
vq.push({x, y+dy});
}
}
}
vector<array<int, 2>> lasts;
for (array<int, 2> pos : steps[step])
hq.push(pos);
for (array<int, 2> pos : steps[step+1])
if (bvert[pos[1]][pos[0]] < n)
hq.push(pos);
else
lasts.push_back(pos);
if (n > 1)
for (array<int, 2> pos : lasts)
hq.push(pos);
while (hq.size())
{
auto [x, y] = hq.front();
hq.pop();
if (bvert[y][x] != -1 && bvert[y][x] < n)
bhrz[y][x] = 0;
else if (bvert[y][x] != -1 && bvert[y][x] == n)
bhrz[y][x] = 1;
for (int dx = -1; dx <= 1; dx+=2)
{
if (c > x+dx && x+dx >= 0 && !visited[y][x+dx] && !seen[y][x+dx])
{
seen[y][x+dx] = true;
min_dist[y][x+dx] = step + 1;
steps[step+1].pb({x+dx, y});
bhrz[y][x+dx] = bhrz[y][x]+1;
if (bhrz[y][x+dx] < n)
hq.push({x+dx, y});
}
}
}
}
int main()
{
cin >> r >> c >> n;
int sx, sy, ex, ey;
cin >> sy >> sx;
cin >> ey >> ex;
sy--, sx--, ey--, ex--;
for (int y = 0; y < r; y++)
{
string s;
white[y] = vector<bool>(c);
visited[y] = vector<bool>(c);
min_dist[y] = vector<int>(c);
bvert[y] = vector<int>(c, -1);
bhrz[y] = vector<int>(c, -1);
seen[y] = vector<bool>(c, false);
cin >> s;
for (int x = 0; x < c; x++)
white[y][x] = s[x] == '.';
}
steps.pb(vector<array<int, 2>>(0));
int current_step = 0;
clean_dfs(sx, sy, 0);
for (auto [x, y] : steps[current_step])
while (!visited[ey][ex] && !seen[ey][ex])
{
steps.pb(vector<array<int, 2>>(0));
bfs(current_step);
current_step++;
for (int i = steps[current_step].size()-1; i >= 0; i--)
{
auto [x, y] = steps[current_step][i];
if (!visited[y][x])
clean_dfs(x, y, current_step);
}
}
cout << min_dist[ey][ex] << "\n";
}
