#include<bits/stdc++.h>
using namespace std;
#define inf (int)2e9
#define _ <<' '<<
#define nl '\n'
void solve(){
int r, c, n, sx, sy, ex, ey;
cin>>r>>c>>n>>sx>>sy>>ex>>ey;
sx--, sy--, ex--, ey--;
set<int> sr[r], sc[c];
int a[r][c];
for(int i = 0; i < r; i++){
for(int j = 0; j < c; j++){
char s;
cin>>s;
a[i][j] = (s == '#');
sr[i].insert(j);
sc[j].insert(i);
}
}
deque<tuple<int,int,int>> dq;
vector d(r, vector(c, inf));
dq.push_back({0, sx, sy});
d[sx][sy] = 0;
while(!dq.empty()){
auto [dis, x, y] = dq.front();
dq.pop_front();
if(dis != d[x][y]) continue;
if(x == ex and y == ey){
cout<<dis;
return;
}
auto f = [&](int w, int nx, int ny){
if(dis + w >= d[nx][ny]) return;
d[nx][ny] = dis + w;
if(w) dq.push_back({dis+1, nx, ny});
else dq.push_front({dis, nx, ny});
};
if(x-1 >= 0 and !a[x-1][y]) f(0, x-1, y);
if(x+1 < r and !a[x+1][y]) f(0, x+1, y);
if(y-1 >= 0 and !a[x][y-1]) f(0, x, y-1);
if(y+1 < c and !a[x][y+1]) f(0, x, y+1);
int dx = abs(x - ex);
int dy = abs(y - ey);
if(min(dx, dy) < n and max(dx, dy) <= n) f(1, ex, ey);
auto row = [&](int z){
auto il = sr[z].upper_bound(y-n);
auto ir = sr[z].lower_bound(y+n);
if(il == sr[z].end() or sr[z].empty() or ir == sr[z].begin()) return;
int l = *il;
int r = *--ir;
for(int i = l; i <= r; i++){
f(1, z, i);
sr[z].erase(i);
}
};
auto col = [&](int z){
auto il = sc[z].upper_bound(x-n);
auto ir = sc[z].lower_bound(x+n);
if(il == sc[z].end() or sc[z].empty() or ir == sc[z].begin()) return;
int l = *il;
int r = *--ir;
for(int i = l; i <= r; i++){
f(1, i, z);
sc[z].erase(i);
}
};
if(x-n >= 0) row(x-n);
if(x+n < r) row(x+n);
if(y-n >= 0) col(y-n);
if(y+n < c) col(y+n);
}
}
signed main(){
ios_base::sync_with_stdio(0);
cin.tie(NULL);cout.tie(NULL);
int t = 1;
//cin>>t;
while(t--) solve();
return 0;
}
