#include <bits/stdc++.h>
using namespace std;
#define int long long
#define pi pair<int, int>
#define vi vector<int>
#define vs vector<string>
#define vb vector<bool>
#define vpi vector<pi>
#define pb push_back
#define all(a) (a).begin(), (a).end()
const int mod = 1e9 + 7;
int n, r, c;
vector<vi> grid, dist, vis;
signed main()
{
ios_base::sync_with_stdio(0);
cin.tie(NULL);
cout.tie(NULL);
cin >> r >> c >> n;
grid.resize(r, vi(c));
dist.resize(r, vi(c, mod));
vis.resize(r, vi(c, 0));
pi st, fn;
cin >> st.first >> st.second >> fn.first >> fn.second;
st.first--;
st.second--;
fn.first--;
fn.second--;
for (int i = 0; i < r; i++)
{
for (int j = 0; j < c; j++)
{
char c;
cin >> c;
grid[i][j] = (c == '#');
}
}
dist[st.first][st.second] = grid[st.first][st.second];
vis[st.first][st.second] = 1;
vpi moves = {{1, 0}, {-1, 0}, {0, 1}, {0, -1}};
queue<pi> q;
q.push(st);
while (q.size())
{
auto p = q.front();
// cout << p.first << ' ' << p.second << '\n';
q.pop();
for (auto mv : moves)
{
pi m = make_pair((p.first + mv.first), (p.second + mv.second));
if (!(m.first >= 0 && m.second >= 0 && m.first < r && m.second < c) || vis[m.first][m.second])
continue;
vis[m.first][m.second] = 1;
q.push(m);
int mn = mod;
if (grid[m.first][m.second] == 0)
{
if (m.first - 1 >= 0)
mn = min(mn, dist[m.first - 1][m.second]);
if (m.second - 1 >= 0)
mn = min(mn, dist[m.first][m.second - 1]);
if (m.first + 1 < r)
mn = min(mn, dist[m.first + 1][m.second]);
if (m.second - 1 < c)
mn = min(mn, dist[m.first][m.second + 1]);
dist[m.first][m.second] = mn;
if (m == fn)
{
cout << dist[fn.first][fn.second] << '\n';
return 0;
}
continue;
}
map<pi, int> mp;
queue<pi> q2;
q2.push(m);
mp[m] = 1;
while (q2.size())
{
auto p2 = q2.front();
q2.pop();
mn = min(mn, dist[p2.first][p2.second]);
for (auto mv2 : moves)
{
pi m2 = make_pair((p2.first + mv2.first), (p2.second + mv2.second));
if (!(m2.first >= 0 && m2.second >= 0 && m2.first < r && m2.second < c) || mp[m2])
continue;
mp[m2] = 1;
if (abs(m.first - m2.first) <= n && abs(m.second - m2.second) <= n && !(abs(m.first - m2.first) == n && abs(m.second - m2.second) == n))
q2.push(m2);
}
}
dist[m.first][m.second] = min(dist[m.first][m.second], mn + 1);
if (dist[st.first][st.second] && (abs(st.first - m.first) <= n && abs(st.second - m.second) <= n && !(abs(st.first - m.first) == n && abs(st.second - m.second) == n)))
{
dist[m.first][m.second] = 1;
}
if (m == fn)
{
cout << dist[fn.first][fn.second] << '\n';
return 0;
}
}
}
}
