#include<bits/stdc++.h>
#include<fstream>
using namespace std;
ifstream fin("WINTER.inp");
ofstream fout("WINTER.out");
#define ll long long
#define pb push_back
#define forr(i, a, b) for(int i = a; i < b; i++)
#define dorr(i, a, b) for(int i = a; i >= b; i--)
#define ld long double
#define vt vector
#include<fstream>
#define fi first
#define se second
#define pll pair<ll, ll>
#define pii pair<int, int>
const ld PI = 3.14159265359;
const int x[4] = {1, -1, 0, 0};
const int y[4] = {0, 0, 1, -1};
const ll mod = 1e9 + 7;
const int mxn = 5e5, mxm = 1e5, sq = 400;
const int base = (1 << 18);
const ll inf = 1e9;
const ld pre = 1e-6;
int r, c, n, sti, stj, eni, enj;
vt<vt<char>>a;
vt<vt<int>>d;
bool inside(int i, int j){
return(i >= 1 && j >= 1 && i <= r && j <= c);
}
signed main(){
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
cin >> r >> c >> n;
a.resize(r + 1, vt<char>(c + 1));
d.resize(r + 1, vt<int>(c + 1));
cin >> sti >> stj >> eni >> enj;
forr(i, 1, r + 1){
forr(j, 1, c + 1){
cin >> a[i][j]; d[i][j] = 1e9;
}
}
deque<pair<int, int>>dq; dq.pb({sti, stj});
d[sti][stj] = 0;
while(!dq.empty()){
auto [i, j] = dq.front(); dq.pop_front();
if(a[i][j] == '.'){
for(int t = 0; t < 4; t++){
int nwi = i + x[t], nwj = j + y[t];
if(inside(nwi, nwj)){
if(d[nwi][nwj] > d[i][j]){
d[nwi][nwj] = d[i][j];
dq.pb({nwi, nwj});
}
}
}
}
for(int ii = i - n; ii <= i + n; ii++){
for(int jj = j - n; jj <= j + n; jj++){
bool ok1 = (ii == i - n || ii == i + n);
bool ok2 = (jj == j - n || jj == j + n);
if(ok1 && ok2)continue;
if(inside(ii, jj)){
if(d[ii][jj] > d[i][j] + 1){
d[ii][jj] = d[i][j] + 1;
dq.push_front({ii, jj});
}
}
}
}
}
cout << d[eni][enj];
return(0);
}
