#include <bits/stdc++.h>
using namespace std;
const int INF = 1e9 + 10;
int main()
{
cin.tie(0)->sync_with_stdio(0);
int n, m, K;
cin >> n >> m >> K;
pair<int, int> A, B;
cin >> A.first >> A.second >> B.first >> B.second;
A.first--, A.second--, B.first--, B.second--;
vector<string> g(n);
for (int i = 0; i < n; i++)
{
cin >> g[i];
}
vector<vector<int>> rgt1(n, vector<int>(m, -1)), rgt2(n, vector<int>(m, -1));
vector<vector<bool>> vis(n, vector<bool>(m));
for (int i = 0; i < n; i++)
{
for (int j = 0; j < m - 1; j++)
{
rgt1[i][j] = j + 1;
}
}
for (int i = 0; i < n - 1; i++)
{
for (int j = 0; j < m; j++)
{
rgt2[i][j] = i + 1;
}
}
auto able = [&](int i, int j)
{
return 0 <= i && i < n && 0 <= j && j < m && !vis[i][j] && g[i][j] == '.';
};
auto near = [&](int i, int j)
{
return min(abs(i - B.first), abs(j - B.second)) < K && max(abs(i - B.first), abs(j - B.second)) <= K;
};
function<int(int, int)> rr1 = [&](int i, int j) -> int
{
if (j == -1 || !vis[i][j])
{
return j;
}
return rgt1[i][j] = rr1(i, rgt1[i][j]);
};
function<int(int, int)> rr2 = [&](int i, int j) -> int
{
if (i == -1 || !vis[i][j])
{
return i;
}
return rgt2[i][j] = rr2(rgt2[i][j], j);
};
vector<vector<int>> dis(n, vector<int>(m, INF));
vector<pair<int, int>> res;
res.push_back(A);
vis[A.first][A.second] = 1;
dis[A.first][A.second] = 0;
while (res.size())
{
vector<pair<int, int>> res2;
while (res.size())
{
auto [i, j] = res.back();
res2.emplace_back(i, j);
res.pop_back();
for (auto &[dx, dy] : vector<pair<int, int>>{{1, 0}, {0, 1}, {-1, 0}, {0, -1}})
{
if (able(i + dx, j + dy))
{
res.emplace_back(i + dx, j + dy);
dis[i + dx][j + dy] = dis[i][j];
vis[i + dx][j + dy] = 1;
if (vis[B.first][B.second])
{
goto found;
}
}
}
}
while (res2.size())
{
auto [i, j] = res2.back();
res2.pop_back();
if (near(i, j))
{
dis[B.first][B.second] = dis[i][j] + 1;
goto found;
}
for (int ii : {max(0, i - K), min(n - 1, i + K)})
{
int jj = rr1(ii, max(0, j - (K - 1)));
while (jj != -1 && jj <= j + (K - 1))
{
res.emplace_back(ii, jj);
dis[ii][jj] = dis[i][j] + 1;
vis[ii][jj] = 1;
jj = rr1(ii, max(0, j - (K - 1)));
}
}
for (int jj : {max(0, j - K), min(m - 1, j + K)})
{
int ii = rr2(max(0, i - (K - 1)), jj);
while (ii != -1 && ii <= i + (K - 1))
{
res.emplace_back(ii, jj);
dis[ii][jj] = dis[i][j] + 1;
vis[ii][jj] = 1;
ii = rr2(max(0, i - (K - 1)), jj);
}
}
}
}
found:
int ans = dis[B.first][B.second];
cout << ans << '\n';
return 0;
}
