#include<bits/stdc++.h>
using namespace std;
//=====================================================================================================================================
#define ll long long
#define ld long double
#define fi first
#define se second
#define pb push_back
#define pll pair<ll, ll>
#define pli pair<ll, int>
#define pil pair<int, ll>
#define pii pair<int, int>
#define BIT(i, mask) ((mask >> (i)) & 1)
#define DAOBIT(i, mask) ((mask ^ (1 << i)))
#define OFFBIT(i, mask) ((mask & ~(1 << (i))))
#define ONBIT(i, mask) ((mask | (1 << (i))))
#define nmax 1000007
//=====================================================================================================================================
const int N = 1e6 + 7;
const ll mod = 1e9 + 6;
const ll MOD = 1e9 + 7;
const ll inf = 1e9;
int r, c, n;
int sx, sy, ex, ey;
vector<vector<char>> a;
vector<vector<int>> dp;
//=====================================================================================================================================
void fre(){
freopen("MINESHAFT.INP", "r", stdin);
freopen("MINESHAFT.out", "w", stdout);
}
ll gcd(ll a, ll b){
return b ? gcd(b, a % b) : a;
}
ll lcm(ll a, ll b){
return (a / gcd(a, b)) * b;
}
int dx[4] = {-1, 1, 0, 0};
int dy[4] = {0, 0, -1, 1};
void sub1(){
deque<pii> dq;
dp.assign(r + 10, vector<int>(c + 10, inf));
dp[sx][sy] = 0;
dq.push_front({sx, sy});
while(!dq.empty()){
pii e = dq.front();
int x = e.fi;
int y = e.se;
dq.pop_front();
for(int p = 0; p < 4; p++){
int nx = x + dx[p];
int ny = y + dy[p];
if(nx < 1 || nx > r || ny < 1 || ny > c) continue;
if(dp[x][y] + (a[nx][ny] == '#') < dp[nx][ny]){
dp[nx][ny] = dp[x][y] + (a[nx][ny] == '#');
if((a[nx][ny] != '#')) dq.push_front({nx, ny});
else dq.push_back({nx, ny});
}
}
}
cout << dp[ex][ey] << '\n';
}
namespace sub2{
int ans = inf;
int d[1007][1007];
int cal(int N, int sx, int sy, int ex, int ey){
ll lx1 = sx - (N - 1), rx1 = sx;
ll ly1 = sy - (N - 1), ry1 = sy;
ll lx2 = ex - (N - 1), rx2 = ex;
ll ly2 = ey - (N - 1), ry2 = ey;
auto gap = [](ll l1, ll r1, ll l2, ll r2) -> ll {
if(r1 < l2) return l2 - r1;
if(r2 < l1) return l1 - r2;
return 0;
};
ll dx = gap(lx1, rx1, lx2, rx2);
ll dy = gap(ly1, ry1, ly2, ry2);
if(dx == 0 && dy == 0) return 1;
ll D = max(dx, dy);
ll steps = (D + N - 1) / N;
return steps + 1;
}
void solve(){
vector<pii> d1, d2;
queue<pii> q;
q.push({sx, sy});
d[sx][sy] = 1;
while(!q.empty()){
pii e = q.front();
int x = e.fi;
int y = e.se;
d1.pb({x, y});
if(x == ex && y == ey){
cout << 0 << '\n';
return;
}
q.pop();
for(int p = 0; p < 4; p++){
int nx = x + dx[p];
int ny = y + dy[p];
if(nx < 1 || nx > r || ny < 1 || ny > c) continue;
if(d[nx][ny]){
continue;
}
if(a[nx][ny] == '#') continue;
d[nx][ny] = 1;
q.push({nx, ny});
}
}
q.push({ex, ey});
d[ex][ey] = 1;
while(!q.empty()){
pii e = q.front();
int x = e.fi;
int y = e.se;
d2.pb({x, y});
q.pop();
for(int p = 0; p < 4; p++){
int nx = x + dx[p];
int ny = y + dy[p];
if(nx < 1 || nx > r || ny < 1 || ny > c) continue;
if(d[nx][ny]){
continue;
}
if(a[nx][ny] == '#') continue;
d[nx][ny] = 1;
q.push({nx, ny});
}
}
for(auto x : d1){
for(auto y : d2){
ans = min(ans, cal(n, x.fi, x.se, y.fi, y.se));
// cout << x.fi << ' ' << x.se << ' ';
// cout << y.fi << ' ' << y.se << ' ';
// cout << cal(n, x.fi, x.se, y.fi, y.se) << '\n';
}
}
cout << ans << '\n';
}
}
//=====================================================================================================================================
int main(){
cin.tie(0)->sync_with_stdio(0);
// fre();
cin >> r >> c >> n;
cin >> sx >> sy >> ex >> ey;
a.resize(r + 10, vector<char>(c + 10));
for(int i = 1; i <= r; i++){
for(int j = 1; j <= c; j++){
cin >> a[i][j];
}
}
if(n == 1){
sub1();
return 0;
}
if(r * c <= 1e3){
sub2 :: solve();
return 0;
}
return 0;
}
