#include<bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define pb push_back
#define eb emplace_back
#define vi vector<int>
#define pi pair<int,int>
#define sz(v) (int)(v).size()
#define all(v) (v).begin(), (v).end()
#define compact(v) (v).erase(unique(all(v)), (v).end())
template<class T> using upq = priority_queue<T, vector<T>, greater<T>>;
template<class T> int lwrbound(const vector<T>& a, const T& b, const int s = 0){return int(lower_bound(s + all(a), b) - a.begin());}
template<class T> int uprbound(const vector<T>& a, const T& b, const int s = 0){return int(upper_bound(s + all(a), b) - a.begin());}
#define FOR(i, a, b) for(int i = (a); i <= (b); i++)
#define ROF(i, a, b) for(int i = (a); i >= (b); i--)
#define sumof(x) accumulate(all(x), 0ll)
#define dbg(x) "[" << #x " = " << (x) << "]"
#define el "\n"
using ll = long long;
using ld = long double;
template<class T> bool ckmx(T& a, const T b){return (a < b ? a = b, true : false);}
template<class T> bool ckmn(T& a, const T b){return (a > b ? a = b, true : false);}
void Main()
{
int R,C, jsize; cin >> R >> C >> jsize;
int sR, sC, eR, eC;
cin >> sR >> sC >> eR >> eC;
vector<vector<char>> a(R + 1, vector<char>(C + 1));
FOR(i, 1, R) FOR(j, 1, C) cin >> a[i][j];
const int dx[4] = {0, 1, -1, 0};
const int dy[4] = {1, 0, 0, -1};
auto init = [&](int x, int y) -> bool{
return (0 < x && x <= R) && (0 < y && y <= C);
};
// white -> expand with 0 distance
// black -> expand until we can't and will increase the distance
vector<vi> dist(R + 1, vi(C + 1, -1));
queue<pi> expand; queue<pair<pi, pi>> operation;
expand.emplace(sR, sC); dist[sR][sC] = 0;
while(sz(expand) + sz(operation)){
// find all nodes that are available
while(sz(expand)){
pi e = expand.front(); expand.pop();
int x = e.fi, y = e.se;
FOR(i, 0, 3){
int u = x + dx[i], v = y + dy[i];
if(!init(u, v) || dist[u][v] != -1) continue;
if(a[u][v] == '.'){
dist[u][v] = dist[x][y];
expand.push(pi(u, v));
}
else{
dist[u][v] = dist[x][y] + 1;
operation.push(make_pair(pi(u, v), pi(jsize - 1, jsize - 1)));
}
}
}
while(sz(operation)){
pair<pi, pi> e = operation.front(); operation.pop();
int x = e.fi.fi, y = e.fi.se, ver = e.se.fi, hor = e.se.se;
if(ver == 0 || hor == 0)
expand.push(pi(x, y));
FOR(i, 0, 3){
int u = x + dx[i], v = y + dy[i];
if(!init(u, v) || dist[u][v] != -1) continue;
int nVer = ver - (dy[i] != 0), nHor = hor - (dx[i] != 0);
if(nVer < 0 || nHor < 0) continue;
dist[u][v] = dist[x][y];
operation.push(make_pair(pi(u, v), pi(nVer, nHor)));
}
}
}
cout << dist[eR][eC] << el;
}
int32_t main()
{
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
#define name "InvMOD"
if(fopen(name".INP", "r")){
freopen(name".INP", "r", stdin);
freopen(name".OUT", "w", stdout);
}
int t = 1; while(t--) Main();
return 0;
}
