#include <bits/stdc++.h>
#define ll long long
using namespace std;
ll r,c,n;
ll calc(ll i, ll j) {
return i*c+j;
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cin >> r >> c >> n;
ll s1,s2,g1,g2;
cin >> s1 >> s2 >> g1 >> g2;
s1--; s2--; g1--; g2--;
vector<string> a(r);
for (int i=0; i<r; i++) {
cin >> a[i];
}
vector<ll> dist(r*c, 1e18);
vector<ll> dist1(r*c, 1e18);
deque<ll> dq, sq;
dq.push_front(calc(s1, s2));
dist[calc(s1,s2)] = 0;
dist1[calc(s1,s2)]=n-1;
sq.push_back(calc(s1,s2));
vector<ll> di = {-1, 1, 0, 0, -1, -1, 1, 1};
vector<ll> dj = {0, 0, -1, 1, -1, 1, -1, 1};
while(!dq.empty()) {
ll u = dq.front();
dq.pop_front();
ll i = u/c; ll j = u%c;
ll d = dist[u];
ll s = dist1[u];
if (d>dist[u] || (d==dist[u] && s>dist1[u])) continue;
if (i==g1 && j==g2) break;
if (s<n-1) {
for (int idx=0; idx<8; idx++) {
ll i1 = i+di[idx];
ll j1 = j+dj[idx];
if (i1>=0 && i1<r && j1>=0 && j1<c) {
ll v = calc(i1, j1);
if (dist[v]>d || (dist[v]==d && dist1[v]>s+1)) {
dist[v] = d;
dist1[v] = s+1;
dq.push_front(v);
}
}
}
}
for (int idx=0; idx<4; idx++) {
ll i1 = i+di[idx];
ll j1 = j+dj[idx];
if (i1>=0 && i1<r && j1>=0 && j1<c) {
ll v = calc(i1, j1);
if (a[i1][j1]=='.') {
if (dist[v]>d || (dist[v]==d && dist1[v]>n-1)) {
dist[v] = d;
dist1[v] = n-1;
dq.push_front(v);
}
}
if (dist[v]>d+1 || (dist[v]==d+1 && dist1[v]>0)) {
dist[v] = d+1;
dist1[v] = 0;
dq.push_back(v);
}
}
}
}
cout << dist[calc(g1,g2)];
}
