#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
int r, c, N;
cin >> r >> c >> N;
int sti, stj, eni, enj;
cin >> sti >> stj >> eni >> enj;
sti -= 1;
stj -= 1;
eni -= 1;
enj -= 1;
vector<vector<char>> a(r, vector<char>(c));
for (int i = 0; i < r; ++i) for (int j = 0; j < c; ++j) cin >> a[i][j];
vector<vector<int>> dist(r, vector<int>(c, r * c + 1));
deque<array<int, 6>> dq;
dq.push_back({sti, stj, -1, -1, r, c});
dist[sti][stj] = 0;
vector<int> dx = {1, 0, -1, 0}, dy = {0, 1, 0, -1};
while (dq.size()) {
int ri = dq.front()[0];
int rj = dq.front()[1];
int mxi = dq.front()[2];
int mxj = dq.front()[3];
int mni = dq.front()[4];
int mnj = dq.front()[5];
dq.pop_front();
for (int k = 0; k < 4; ++k) {
int ni = ri + dx[k];
int nj = rj + dy[k];
if (ni < 0 || nj < 0 || ni >= r || nj >= c) continue;
int nmxi = max(mxi, ni);
int nmni = min(mni, ni);
int nmxj = max(mxj, nj);
int nmnj = min(mnj, nj);
int add = ((nmxi - nmni >= N || nmxj - nmnj >= N) && a[ni][nj] == '#');
if (a[ni][nj] == '#' && a[ri][rj] == '.') add = 1;
if (add == 0) {
if (dist[ni][nj] > dist[ri][rj]) {
dist[ni][nj] = dist[ri][rj];
if (a[ni][nj] == '#') dq.push_front({ni, nj, nmxi, nmxj, nmni, nmnj});
else dq.push_front({ni, nj, -1, -1, r, c});
}
} else {
if (dist[ni][nj] > dist[ri][rj] + add) {
dist[ni][nj] = dist[ri][rj] + add;
dq.push_front({ni, nj, ni, nj, ni, nj});
}
}
}
}
//~ for (int i = 0; i < r; ++i) {
//~ for (int j = 0; j < c; ++j) {
//~ cout << dist[i][j] << " ";
//~ }
//~ cout << "\n";
//~ }
cout << dist[eni][enj] << "\n";
}
