#include <bits/stdc++.h>
using namespace std;
int R, C, N;
bool isBest(int d1, int d2, pair<int, int> p){
int mn1 = min(d1, d2);
int mx1 = max(d1, d2);
int mn2 = min(p.first, p.second);
int mx2 = max(p.first, p.second);
if(!((mx1 <= N && mn1 < N) || (mx2 <= N && mn2 < N))) return false;
if(mx1 == mx2) return mn1 < mn2;
else return mx1 < mx2;
}
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
cin >> R >> C >> N;
int Sr, Sc, Gr, Gc; cin >> Sr >> Sc >> Gr >> Gc; Sr--; Sc--; Gr--; Gc--;
vector<string> v(R);
for(auto &i : v) cin >> i;
vector<vector<int>> dist(R, vector<int>(C, 1e9));
vector<vector<bool>> vis(R, vector<bool>(C, false));
dist[Sr][Sc] = 0;
priority_queue<tuple<int, int, int>> q; q.push({0, Sr, Sc});
while(!q.empty()){
int i = get<1>(q.top()); int j = get<2>(q.top()); q.pop();
if(vis[i][j]) continue;
vis[i][j] = true;
// cout << "i " << i+1 << " j " << j+1 << " dist " << dist[i][j] << "\n";
for(int ai = -1; ai <= 1; ai++){
for(int aj = -1; aj <= 1; aj++){
if(ai * aj != 0 || i + ai < 0 || i + ai >= R || j + aj < 0 || j + aj >= C) continue;
int ni = i + ai; int nj = j + aj;
if(v[ni][nj] == '.' && dist[ni][nj] > dist[i][j]){
dist[ni][nj] = dist[i][j];
q.push({-dist[ni][nj], ni, nj});
}
}
}
for(int ai = -N; ai <= N; ai++){
for(int aj = -N; aj <= N; aj++){
if(min(abs(ai), abs(aj)) == N) continue;
if(i + ai < 0 || i + ai >= R || j + aj < 0 || j + aj >= C) continue;
int ni = i + ai; int nj = j + aj;
// cout << "ni " << ni+1 << " nj " << nj+1 << "\n";
if(dist[ni][nj] > dist[i][j]+1){
dist[ni][nj] = dist[i][j]+1;
q.push({-dist[ni][nj], ni, nj});
}
}
}
}
cout << dist[Gr][Gc] << "\n";
}
