#include<bits/stdc++.h>
using namespace std;
#define int long long
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define isz(x) ((int)(x).size())
#define sumof(x) accumulate(all(x), 0ll)
const int dx[]={1, -1, 0, 0, 0}, dy[]={0, 0, 1, -1, 0};
int n, r, c;
int sr, sc, gr, gc;
void solve(){
cin >> r >> c >> n;
cin >> sr >> sc >> gr >> gc;
vector<vector<char>> a(r+1, vector<char>(c+1));
vector<vector<int>> dist(r+1, vector<int>(c+1, 1e9));
for (int i=1; i<=r; ++i) for (int j=1; j<=c; ++j) cin >> a[i][j];
auto bfs_white=[&](vector<pair<int, int>> roots, int distance) -> vector<pair<int, int>> {
queue<pair<int, int>> q;
vector<pair<int, int>> found;
for (auto &i:roots){
int u=i.first, v=i.second;
for (int j=0; j<5; ++j) for (int k=1; k<=n; ++k){
int x=u+dx[j]*k, y=v+dy[j]*k;
if (x<1 || y<1 || x>r || y>c || dist[x][y]<1e9 || a[x][y]=='#') continue;
dist[x][y]=distance;
q.emplace(x, y);
}
}
while (q.size()){
int u=q.front().first, v=q.front().second;
q.pop();
for (int i=0; i<4; ++i){
int x=u+dx[i], y=v+dy[i];
if (x<1 || y<1 || x>r || y>c || dist[x][y]<1e9) continue;
if (a[x][y]=='.'){
q.emplace(x, y);
dist[x][y]=distance;
}else{
dist[x][y]=distance+1;
found.emplace_back(x, y);
}
}
}
return found;
};
auto bfs_black=[&](vector<pair<int, int>> roots, int distance) -> vector<pair<int, int>> {
vector<pair<int, int>> found=roots;
for (auto &i:roots){
int u=i.first, v=i.second;
for (int j=0; j<4; ++j) for (int k=1; k<n; ++k){
int x=u+dx[j]*k, y=v+dy[j]*k;
if (x<1 || y<1 || x>r || y>c || dist[x][y]<1e9 || a[x][y]=='.') continue;
dist[x][y]=distance;
found.emplace_back(x, y);
}
}
return found;
};
int cur=0;
vector<pair<int, int>> roots{{sr, sc}};
while (dist[gr][gc]>=1e9){
bfs_white(roots, cur).swap(roots);
bfs_black(roots, ++cur).swap(roots);
}
cout << dist[gr][gc];
}
int32_t main(){
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
int ntests=1;
// cin >> ntests;
for (int i=1; i<=ntests; ++i) solve();
return 0;
}
