#include <bits/stdc++.h>
using namespace std;
const int MX = 6e6 + 5;
const int dx[4] = {1, 0, -1, 0}, dy[4] = {0, 1, 0, -1};
int N, R, C;
int sc, sr, gc, gr;
string s[MX];
vector<vector<int>> par;
int nxt(int r, int c) { // row, column
return par[r][c] == c ? c : par[r][c] = nxt(r, par[r][c]);
}
void merge(int r, int c, int cc) {
if(cc >= C) return;
c = nxt(r, c); cc = nxt(r, cc);
if(c == cc) return;
par[r][c] = cc;
}
int main() {
cin.tie(0); ios_base::sync_with_stdio(0);
cin >> R >> C >> N;
cin >> sr >> sc >> gr >> gc;
for(int i = 0; i < R; i++) cin >> s[i];
sc--, sr--, gc--, gr--;
par = vector<vector<int>>(R, vector<int>(C));
for(int i = 0; i < R; i++) {
for(int j = 0; j < C; j++) {
par[i][j] = j;
}
}
vector<vector<int>> dist(R, vector<int>(C, 1e9));
vector<vector<bool>> vis(R, vector<bool>(C));
deque<pair<int,int>> dq;
dq.push_back({sr, sc});
dist[sr][sc] = 0;
while(!dq.empty()) {
auto [x, y] = dq.front(); dq.pop_front();
if(vis[x][y]) continue;
vis[x][y] = 1;
for(int k = 0; k < 4; k++) {
int r = x + dx[k], c = y + dy[k];
if(r >= 0 && r < R && c >= 0 && c < C && dist[r][c] > dist[x][y] && s[r][c] == '.') {
dist[r][c] = dist[x][y];
dq.push_front({r, c});
if(x == r && nxt(r, y) != nxt(r, c)) merge(r, min(y, c), max(y, c));
}
}
for(int r = max(0, x - N); r <= min(R - 1, x + N); r++) {
int b = abs(x - r) == N;
int c = nxt(r, max(0, y - N + b));
while(c <= min(C - 1, y + N - b)) {
if(dist[r][c] > dist[x][y] + 1) {
dist[r][c] = dist[x][y] + 1;
dq.push_back({r, c});
}
int nc = nxt(r, c) + 1;
merge(r, c, nc);
c = nc;
}
}
}
cout << dist[gr][gc] << '\n';
}
