#include <bits/stdc++.h>
using namespace std;
int dx[] = {1, -1, 0, 0};
int dy[] = {0, 0, -1, 1};
vector<vector<char>> v;
vector<vector<int>> dp;
vector<set<int>> s;
queue<pair<int, int>> q;
int f[101][101];
void flood_fill(int i, int j, int val) {
for(int d = 0; d < 4; d++) {
int a = i + dx[d];
int b = j + dy[d];
if(v[a][b] == '.' && s[a].find(b) != s[a].end()) {
q.push({a, b});
s[a].erase(b);
dp[a][b] = val;
flood_fill(a, b, val);
}
}
}
int32_t main() {
ios_base::sync_with_stdio(false);
cin.tie();
cout.tie();
int n, m, d;
cin >> n >> m >> d;
v.resize(n + 2, vector<char>(m + 2));
dp.resize(n + 2, vector<int>(m + 2));
s.resize(n + 2);
int si, sj, ei, ej;
cin >> si >> sj >> ei >> ej;
for(int i = 1; i <= n; i++) {
for(int j = 1; j <= m; j++) {
cin >> v[i][j];
s[i].insert(j);
dp[i][j] = 1e9;
}
}
dp[si][sj] = 0;
s[si].erase(sj);
q.push({si, sj});
flood_fill(si, sj, 0);
while(!q.empty()) {
auto [a, b] = q.front();
q.pop();
if(a == ei && b == ej) {
cout << dp[a][b];
return 0;
}
// deci mergem (a - d, b - d) -> (a + d, b + d)
// fara colturi
int p1 = b - d, p2 = b + d, aux;
for(int i = max(1, a - d); i <= min(n, a + d); i++) {
if(i == a - d || i == a + d) {
p1++, p2--;
}
auto it = s[i].lower_bound(p1);
vector<int> de;
while(it != s[i].end() && *it <= p2) {
aux = *it;
dp[i][aux] = dp[a][b] + 1;
q.push({i, aux});
if((i == a - d || i == a + d || aux == b + d || aux == b - d) && (v[i][aux] == '.' || v[i][aux - 1] == '.' || v[i - 1][aux] == '.'|| v[i][aux + 1] == '.' || v[i + 1][aux] == '.')) {
de.push_back(aux);
}
it++;
s[i].erase(aux);
}
for(auto ip : de) {
for(int dir = 0; dir < 4; dir++) {
int ii = i + dx[dir];
int jj = ip + dy[dir];
if(v[ii][jj] == '.' && s[ii].find(jj) != s[ii].end()) {
// continue;
s[ii].erase(jj);
dp[ii][jj] = dp[i][ip];
q.push({ii, jj});
flood_fill(ii, jj, dp[ii][jj]);
}
}
if(v[i][ip] == '.' && s[i].find(ip) != s[i].end()) {
s[i].erase(ip);
flood_fill(i, ip, dp[i][ip]);
}
}
if(i == a - d || i == a + d) {
p1--, p2++;
}
}
}
assert(0);
return 0;
}
