#include <bits/stdc++.h>
using namespace std;
struct state {
int a, b, si, sj, ji, jj;
};
int dx[] = {1, -1, 0, 0};
int dy[] = {0, 0, -1, 1};
vector<vector<bool>> v, f;
vector<vector<int>> dp;
bool in(int a, int b, int x, int y, int i, int j) {
if(v[i][j] == 1) {
return 1;
}
if(a <= i && i <= x && b <= j && j <= y) {
return 1;
}
return 0;
}
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<bool>(m + 2));
f.resize(n + 2, vector<bool>(m + 2));
dp.resize(n + 2, vector<int>(m + 2));
int s1, s2, e1, e2;
cin >> s1 >> s2 >> e1 >> e2;
for(int i = 1; i <= n; i++) {
for(int j = 1; j <= m; j++) {
char ch;
cin >> ch;
if(ch == '.') {
ch = 1;
} else {
ch = 0;
}
v[i][j] = ch;
dp[i][j] = 1e9;
}
}
dp[s1][s2] = 0;
deque<state> dq;
dq.push_front({s1, s2, -1, -1, -1, -1});
int val = 0, i, j;
while(!dq.empty()) {
auto [a, b, si, sj, ji, jj] = dq.front();
// cout << a << " " << b << ": " << dp[a][b] << '\n';
dq.pop_front();
for(int dd = 0; dd < 4; dd++) {
i = a + dx[dd];
j = b + dy[dd];
if(min(i, j) < 1 || i > n || j > m) {
continue;
}
val = 1 - in(si, sj, ji, jj, i, j);
if(dp[a][b] + val < dp[i][j]) {
if(!val) {
dp[i][j] = dp[a][b];
dq.push_front({i, j, si, sj, ji, jj});
} else {
dp[i][j] = dp[a][b] + 1;
dq.push_back({i, j, a - d + 1, b - d, a, b - 1});
dq.push_back({i, j, a, b - d, a + d - 1, b - 1});
dq.push_back({i, j, a - 1, b - d + 1, a - d, b});
dq.push_back({i, j, a - 1, b, a - d, b + d - 1});
dq.push_back({i, j, a, b + 1, a - d + 1, b - d});
dq.push_back({i, j, a - d + 1, b + 1, a, b + d});
dq.push_back({i, j, a - d, b, a - 1, b + d - 1});
dq.push_back({i, j, a - d, b - d + 1, a - 1, b});
}
}
}
}
cout << dp[e1][e2];
return 0;
}
