#include <bits/stdc++.h>
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define int long long
#define yes() cout << "YES\n"
#define no() cout << "NO\n"
using namespace std;
using ll = long long;
using ull = unsigned long long;
using ld = long double;
const int inf = 1e18;
const int mod = 1e9 + 7;
const int maxn = 1e7 + 5e6;
const int mod1 = 998244353;
const int mod2 = 1e18 + 1;
const int mod3 = 1e9 + 9;
const int mod4 = 333333333;
const int mod5 = 200000;
const int mod6 = 10007;
const int k = 300;
const int w = 1e5;
const ld EPS = 1e-8;
int LOG = 30;
struct e {
int x, y, p, q;
};
void solve() {
int k, n, m;
cin >> n >> m >> k;
int x1, y1, x2, y2;
cin >> x1 >> y1 >> x2 >> y2;
x1--, y1--, x2--, y2--;
vector<vector<int>> d(n, vector<int> (m, inf));
d[x1][y1] = 0;
vector<string> a(n);
for (auto& i : a) cin >> i;
queue<pair<int, int>> q1;
queue<e> q2;
vector<pair<int, int>> tmp = {{1, 0}, {-1, 0}, {0, 1}, {0, -1}};
q1.push({x1, y1});
while (q1.size()) {
while (q1.size()) {
auto [x, y] = q1.front();
q1.pop();
for (auto& [dx, dy] : tmp) {
int nx = x + dx, ny = y + dy;
if (!(0 <= nx && nx < n && 0 <= ny && ny < m && d[nx][ny] == inf)) continue;
if (a[nx][ny] == '.') {
d[nx][ny] = d[x][y];
q1.push({nx, ny});
} else {
d[nx][ny] = d[x][y] + 1;
q2.push({nx, ny, 0, 0});
}
}
}
while (q2.size()) {
auto [x, y, p, q] = q2.front();
q2.pop();
if (p == k - 1 || q == k - 1) q1.push({x, y});
for (auto& [dx, dy] : tmp) {
int nx = x + dx, ny = y + dy;
if (!(0 <= nx && nx < n && 0 <= ny && ny < m && d[nx][ny] == inf)) continue;
if (p + abs(dx) < k && q + abs(dy) < k) {
d[nx][ny] = d[x][y];
q2.push({nx, ny, p + abs(dx), q + abs(dy)});
}
}
}
}
cout << d[x2][y2] << "\n";
}
signed main() {
// cout.precision(16);
ios::sync_with_stdio(false);
cin.tie(nullptr);
int t = 1;
// cin >> t;
while (t--) {
solve();
}
}
