#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define pp pair<int, int>
#define F first
#define S second
const int N = 1010;
const int INF = 1e9;
int n, m, k;
int X1, Y1, X2, Y2;
char a[N][N];
int dist[N][N];
int dx[4] = {-1, 1, 0, 0};
int dy[4] = {0, 0, -1, 1};
bool bio[N][N];
queue<pp> q;
bool inb(int x, int y){
return (x >= 0 && x < n && y >= 0 && y < m);
}
void fill(int l1, int l2, int r1, int r2, int x){
for (int i = l1; i <= l2; ++i)
for (int j = r1; j <= r2; ++j){
if (!inb(i, j)) continue;
dist[i][j] = min(dist[i][j], x);
if (!bio[i][j]) q.push({i, j}), bio[i][j] = 1;
}
}
int main(){
cin >> n >> m >> k;
cin >> X1 >> Y1 >> X2 >> Y2;
--X1, --Y1, --X2, --Y2;
for (int i = 0; i < n; ++i)
for (int j = 0; j < m; ++j)
cin >> a[i][j];
for (int i = 0; i < n; ++i)
for (int j = 0; j < m; ++j)
dist[i][j] = INF;
dist[X1][Y1] = 0;
vector<pair<int, pp> > v;
for (int i = 0; i < n; ++i)
for (int j = 0; j < m; ++j)
v.pb({abs(i - X1) + abs(j - Y1), {i, j}});
sort(v.begin(), v.end());
q.push({X1, Y1}); bio[X1][Y1] = 1;
while (!q.empty()){
int x = q.front().F, y = q.front().S; q.pop();
for (int i = 0; i < 4; ++i){
if (inb(x + dx[i], y + dy[i]) && a[x + dx[i]][y + dy[i]] == '.'){
dist[x + dx[i]][y + dy[i]] = min(dist[x + dx[i]][y + dy[i]], dist[x][y]);
if (!bio[x + dx[i]][y + dy[i]]) q.push({x + dx[i], y + dy[i]}), bio[x + dx[i]][y + dy[i]] = 1;
}
}
fill(x - k + 1, x + k - 1, y - k, y + k, dist[x][y] + 1);
fill(x - k, x + k, y - k + 1, y + k - 1, dist[x][y] + 1);
}
cout << dist[X2][Y2];
return 0;
}
