#include <bits/stdc++.h>
using namespace std;
#define dbg(x) x
#define prt(x) dbg(cerr << x)
#define pv(x) dbg(cerr << #x << " = " << x << '\n')
#define pv2(x) dbg(cerr << #x << " = " << x.first << ',' << x.second << '\n')
#define parr(x) dbg(prt(#x << " = { "); for (auto y : x) prt(y << ' '); prt("}\n");)
#define parr2(x) dbg(prt(#x << " = { "); for (auto [y, z] : x) prt(y << ',' << z << " "); prt("}\n");)
#define parr2d(x) dbg(prt(#x << ":\n"); for (auto arr : x) {parr(arr);} prt('\n'));
#define parr2d2(x) dbg(prt(#x << ":\n"); for (auto arr : x) {parr2(arr);} prt('\n'));
/*
*/
int dx[4] = {1, -1, 0, 0};
int dy[4] = {0, 0, 1, -1};
const int inf = 2e9 + 5;
int main() {
ios::sync_with_stdio(0); cin.tie(0);
int n, m, k;
cin >> n >> m >> k;
int i0, j0, i1, j1;
cin >> i0 >> j0 >> i1 >> j1;
i0--; j0--; i1--; j1--;
vector<string> a(n);
for (int i = 0; i < n; i++) {
cin >> a[i];
}
function<bool(int, int)> ok = [&] (int i, int j) {
return i >= 0 && i < n && j >= 0 && j < m;
};
if (k == 1) {
vector<vector<int>> dist(n, vector<int>(m, inf));
deque<array<int, 3>> q;
q.push_back({i0, j0, 0});
dist[i0][j0] = 0;
while (q.size()) {
int i = q[0][0], j = q[0][1], _d = q[0][2];
q.pop_front();
if (dist[i][j] != _d) continue;
for (int d = 0; d < 4; d++) {
int ni = i + dx[d], nj = j + dy[d];
if (!ok(ni, nj)) continue;
if (a[ni][nj] == '.') {
if (dist[i][j] < dist[ni][nj]) {
dist[ni][nj] = dist[i][j];
q.push_front({ni, nj, dist[i][j]});
}
} else {
if (dist[i][j] + 1 < dist[ni][nj]) {
dist[ni][nj] = dist[i][j] + 1;
q.push_back({ni, nj, dist[i][j] + 1});
}
}
}
}
cout << dist[i1][j1] << '\n';
} else if (n * m <= 1000) {
vector<vector<int>> dist(n, vector<int>(m, inf));
dist[i0][j0] = 0;
vector<vector<bool>> vis(n, vector<bool>(m, false));
priority_queue<array<int, 3>> q;
q.push({0, i0, j0});
vis[i0][j0] = true;
while (q.size()) {
int ed = -q.top()[0], i = q.top()[1], j = q.top()[2];
q.pop();
if (ed != dist[i][j]) continue;
for (int ni = max(i - k, 0); ni <= min(i + k, n - 1); ni++) {
for (int nj = max(j - k, 0); nj <= min(j + k, m - 1); nj++) {
if (ni == i && nj == j) continue;
if (abs(i - ni) + abs(j - nj) == 1 && a[ni][nj] == '.') {
if (dist[i][j] < dist[ni][nj]) {
dist[ni][nj] = dist[i][j];
q.push({-dist[ni][nj], ni, nj});
}
} else {
if (dist[i][j] + 1 < dist[ni][nj]) {
dist[ni][nj] = dist[i][j] + 1;
q.push({-dist[ni][nj], ni, nj});
}
}
}
}
}
cout << dist[i1][j1] << '\n';
}
}
