#include <bits/stdc++.h>
using namespace std;
int r,c,n;
struct DSU{
vector < vector < pair < int , int > > > par;
DSU(int x , int y){
par.assign(x+1 , vector < pair < int , int > > (y+1));
for(int i = 0;i<=x;i++)for(int j = 0;j<=y;j++)par[i][j] = {i,j};
}
inline pair < int , int > find(pair < int , int > a){
if(a.first < 0)a.first = 0;
if(a.first >= r)a.first = r-1;
if(a.second < 0)a.second = 0;
if(a.second >= c)a.second = c-1;
if(par[a.first][a.second] == a)return a;
return par[a.first][a.second] = find(par[a.first][a.second]);
}
inline void merge(pair < int , int > a , pair < int , int > b){
pair < int , int > fa = find(a);
par[fa.first][fa.second] = find(b);
}
};
void solve(){
cin >> r >> c >> n;
DSU dsuhor(r,c) , dsuver(r,c);
pair < int , int > s,g;
cin >> s.first >> s.second >> g.first >> g.second;
s.first--;s.second--;g.first--;g.second--;
int grid[r][c];
for(int i = 0;i<r;i++){//1 = # , 0 = .
string str;cin >> str;
for(int j = 0;j<c;j++){
grid[i][j] = str[j] == '#';
}
}
queue < pair < int , int > > bfs[r+c+1];
bfs[0].push(s);
vector < vector < int > > vis(r , vector < int > (c,0));
for(int curdist = 0;curdist < (r+c+1);curdist++){
while(bfs[curdist].size()){
pair < int , int > p = bfs[curdist].front();
bfs[curdist].pop();
if(p == g){
cout << curdist << '\n';
return;
}
if(vis[p.first][p.second])continue;
vis[p.first][p.second] = 1;
dsuhor.merge(p,{p.first,p.second+1});
dsuver.merge(p,{p.first+1,p.second});
if((p.first + n) < r){// ({n,-n} , {n,n})
pair < int , int > dfs = dsuhor.find({p.first + n , p.second - n + 1});
while(dfs.second < (p.second + n)){
bfs[curdist+1].push(dfs);
if(dfs.second == (c-1))break;
dfs = dsuhor.find({dfs.first , dfs.second+1});
}
}
if((p.first - n) >= 0){// ({-n,-n} , {-n,n})
pair < int , int > dfs = dsuhor.find({p.first - n , p.second - n + 1});
while(dfs.second < (p.second + n)){
bfs[curdist+1].push(dfs);
if(dfs.second == (c-1))break;
dfs = dsuhor.find({dfs.first , dfs.second+1});
}
}
if((p.second + n) < c){// ({-n,n} , {n,n})
pair < int , int > dfs = dsuver.find({p.first - n + 1, p.second + n});
while(dfs.first < (p.first + n)){
bfs[curdist+1].push(dfs);
if(dfs.first == (r-1))break;
dfs = dsuver.find({dfs.first+1 , dfs.second});
}
}
if((p.second - n) >= 0){// ({-n,-n} , {n,-n})
pair < int , int > dfs = dsuver.find({p.first - n + 1, p.second - n});
while(dfs.first < (p.first + n)){
bfs[curdist+1].push(dfs);
if(dfs.first == (r-1))break;
dfs = dsuver.find({dfs.first+1 , dfs.second});
}
}
if(p.first != 0 and grid[p.first-1][p.second] == 0){
bfs[curdist].push({p.first-1,p.second});
}
if(p.second != 0 and grid[p.first][p.second-1] == 0){
bfs[curdist].push({p.first,p.second-1});
}
if(p.first != (r-1) and grid[p.first+1][p.second] == 0){
bfs[curdist].push({p.first+1,p.second});
}
if(p.second != (c-1) and grid[p.first][p.second+1] == 0){
bfs[curdist].push({p.first,p.second+1});
}
if((abs(g.first - p.first) <= n and abs(g.second - p.second) <= (n-1)) or (abs(g.first - p.first) <= (n-1) and abs(g.second - p.second) <= n)){
bfs[curdist+1].push(g);
}
}
}
cout << -1 << '\n';
}
signed main(){
ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
int testcase = 1;//cin >> testcase;
while(testcase--)solve();
//cout<<endl<<fixed<<setprecision(2)<<1000.0 * clock() / CLOCKS_PER_SEC<< " milliseconds ";
}
