#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#include <bits/stdc++.h>
//#define int long long
#define ll long long
#define fi first
#define se second
#define pb push_back
#define all(lmao) lmao.begin(), lmao.end()
using namespace std;
typedef pair<int,int> pii;
typedef tuple<ll,int,int> tp;
const int N = 6e6 + 5;
const ll oo = 1e14 + 1;
const int mod = 1e9 + 7;
//const ll oo = 5e18;
const int ha[4] = {1, -1, 0, 0};
const int co[4] = {0, 0, 1, -1};
const int tx[4] = {1, 1, -1, -1};
const int ty[4] = {1, -1, -1, 1};
int m, n, k, xt, yt, xs, ys;
ll ans;
vector<ll> f[N];
vector<int> a[N], ph[N], pc[N];
priority_queue<tp, vector<tp>, greater<tp>> q;
bool kt(int x,int y){
return x >= 1 && x <= m && y >= 1 && y <= n;
}
int row(int u,int v){
return (ph[u][v] == v ? v : ph[u][v] = row(u, ph[u][v]));
}
int col(int u,int v){
return (pc[u][v] == u ? u : pc[u][v] = col(pc[u][v], v));
}
void conduct(ll val,int x,int y){
int l = max(1, x - k + 1), r = min(m, x + k - 1), pl = max(1, y - k + 1), pr = min(n, y + k - 1);
if(xt >= l && xt <= r && yt >= pl && yt <= pr) ans = min(ans, val + 1);
if(l - 1 >= 1){
int lx = l - 1, g = pr;
while(ph[lx][g] >= pl){
g = ph[lx][g];
if(f[lx][g] > val + 1 + a[lx][g]) f[lx][g] = val + 1 + a[lx][g], q.push({f[lx][g], lx, g});
if(!ph[lx][g]) break;
ph[lx][g]--;
ph[lx][g] = row(lx, ph[lx][g]);
}
}
if(r + 1 <= m){
int lx = r + 1, g = pr;
while(ph[lx][g] >= pl){
g = ph[lx][g];
if(f[lx][g] > val + 1 + a[lx][g]) f[lx][g] = val + 1 + a[lx][g], q.push({f[lx][g], lx, g});
if(!ph[lx][g]) break;
ph[lx][g]--;
ph[lx][g] = row(lx, ph[lx][g]);
}
}
if(pl - 1 >= 1){
int g = r, ly = pl - 1;
while(pc[g][ly] >= l){
g = pc[g][ly];
if(f[g][ly] > val + 1 + a[g][ly]) f[g][ly] = val + 1 + a[g][ly], q.push({f[g][ly], g, ly});
if(!pc[g][ly]) break;
pc[g][ly]--;
pc[g][ly] = col(pc[g][ly], ly);
}
}
if(pr + 1 <= n){
int g = r, ly = pr + 1;
while(pc[g][ly] >= l){
g = pc[g][ly];
if(f[g][ly] > val + 1 + a[g][ly]) f[g][ly] = val + 1 + a[g][ly], q.push({f[g][ly], g, ly});
if(!pc[g][ly]) break;
pc[g][ly]--;
pc[g][ly] = col(pc[g][ly], ly);
}
}
}
signed main(){
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define task "v"
if(fopen(task ".inp","r")){
freopen(task ".inp","r",stdin);
freopen(task ".out","w",stdout);
}
cin >> m >> n >> k;
cin >> xs >> ys >> xt >> yt;
for(int i = 1; i <= m; i ++){
string s; cin >> s;
f[i].pb(oo);
a[i].pb(0);
ph[i].pb(0);
pc[i].pb(0);
for(int j = 0; j < n; j ++){
f[i].pb(oo);
pc[i].pb(0);
ph[i].pb(j + 1);
if(s[j] == '.') a[i].pb(0);
else a[i].pb(1);
}
f[i].pb(oo);
a[i].pb(0);
ph[i].pb(0);
pc[i].pb(0);
}
for(int i = 1; i <= n + 1; i ++) pc[0].pb(0);
for(int i = 1; i <= n; i ++){
for(int j = 1; j <= m; j ++){
pc[j][i] = j;
}
}
// for(int i = 1; i <= m; i ++){
// for(int j = 1; j <= n; j ++) cout << a[i][j] << " ";
// cout << "\n";
// }
f[xs][ys] = 0;
q.push({0, xs, ys});
ans = oo;
while(!q.empty()){
ll val;
int px, py; tie(val, px, py) = q.top();
// int x = q.front().fi;
// int y = q.front().se;
q.pop();
if(val > f[px][py]) continue;
if(px == xt && py == yt) ans = min(ans, f[px][py]);
conduct(val, px, py);
for(int d = 0; d < 4; d ++){
int x = px + ha[d];
int y = py + co[d];
if(!kt(x, y) || f[x][y] <= f[px][py] + a[x][y]) continue;
f[x][y] = f[px][py] + a[x][y];
q.push({f[x][y], x, y});
if(ph[x][y]){
ph[x][y]--;
ph[x][y] = row(x, ph[x][y]);
}
if(pc[x][y]){
pc[x][y]--;
pc[x][y] = col(pc[x][y], y);
}
conduct(val, x, y);
}
}
cout << min(ans, f[xt][yt]);
}
/*
6 6 3
5 4
2 1
###.#.
#..#..
...###
###.##
..####
#.#...
*/
