#include <bits/stdc++.h>
using namespace std;
const auto start_time = std::chrono::high_resolution_clock::now();
void timecalculater(){
    #ifndef ONLINE_JUDGE
    auto end_time = std::chrono::high_resolution_clock::now();
    std::chrono::duration<double> diff = end_time-start_time;
    cerr<<"Time Taken : "<<diff.count()<<"\n";
    #endif
}
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
void __print(int x) {cout << x;}
void __print(long x) {cout << x;}
void __print(long long x) {cout << x;}
void __print(unsigned x) {cout << x;}
void __print(unsigned long x) {cout << x;}
void __print(unsigned long long x) {cout << x;}
void __print(float x) {cout << x;}
void __print(double x) {cout << x;}
void __print(long double x) {cout << x;}
void __print(char x) {cout << '\'' << x << '\'';}
void __print(const char *x) {cout << '\"' << x << '\"';}
void __print(const string &x) {cout << '\"' << x << '\"';}
void __print(bool x) {cout << (x ? "true" : "false");}
template<typename T, typename V>
void __print(const pair<T, V> &x) {cout << '{'; __print(x.first); cout << ','; __print(x.second); cout << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cout << '{'; for (auto &i: x) cout << (f++ ? "," : ""), __print(i); cout << "}";}
void _print() {cout << "]\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cout << ", "; _print(v...);}
#ifndef ONLINE_JUDGE
#define dbg(x...) cout << "[" << #x << "] = ["; _print(x)
#else
#define dbg(x...)
#endif
#define fastio  cin.sync_with_stdio(0); cin.tie(0);cin.exceptions(cin.failbit);
#define rep(i, n) for(int i = 0; i < (n); ++i)
#define repA(i, a, n) for(int  i = a; i <= (n); ++i)
#define all(x) x.begin(), x.end()
#define sz(x) (int) (x).size()
#define fill(a,v) memset(a, v, sizeof(a))
#define fst first
#define snd second
#define mp make_pair
#define pb push_back
#define endl '\n'
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<long long, long long> pll;
typedef vector<int> vi;
typedef vector<double> vd;
typedef vector<long long int> vll;
typedef vector<pii> vii;
ll p=1e9+7;
const int N=2e5+5;
int main() {
  
    fastio;
    int T=1;
    // cin>>T;
    while(T--){
        int h,k,w;cin>>h>>w>>k;
        int x1,y1,x2,y2;
        cin>>x1>>y1>>x2>>y2;x1--;y1--;x2--;y2--;
        int ans[h][w];
        fill(ans,-1);
        char a[h][w];
        rep(i,h)rep(j,w)cin>>a[i][j];
        queue<pair<pair<int,int>,int> > q;
        q.push({{x1,y1},0});
        set<int> col[w];
        set<int> row[h];
        rep(i,h){
        	rep(j,w){
        		if(i==x1&&j==y1)continue;
        		row[i].insert(j);
        	}
        }
        rep(j,w){
        	rep(i,h){
        		if(i==x1&&j==y1)continue;
        		col[j].insert(i);
        	}
        }
        while(!q.empty()){
        	pair<pair<int,int>,int> p=q.front();q.pop();
        	int i=p.fst.fst;int j=p.fst.snd;int d=p.snd;
        	ans[i][j]=d;
        	auto it=row[i].lower_bound(j);
        	while(1){
        		if(sz(row[i])==0){
        			break;
        		}
        		if(it==row[i].end()){
        			it--;
        		}
        		int f=0;
        		int y=*it;
        		if(it==row[i].begin()){
        			f=1;
        		}
        		if(y>=j){
        			if(f)break;
        			it--;continue;
        		}

        		if(y<=(j)&&y>=(j-k)){
        			if(a[i][y]!='.'){
        				break;
        			}

        			q.push({{i,y},d+1});
        			if(f){
        				row[i].erase(it);
        				col[y].erase(col[y].find(i));
        				break;
        			}
        			row[i].erase(it--);
        			col[y].erase(col[y].find(i));

        		}
        		else{
        			break;
        		}
        	}
        	it=row[i].lower_bound(j);
        	while(it!=row[i].end()){
        		int y=*it;
        		if(y<=(j+k)&&y>=(j)){
        			if(a[i][y]!='.'){
        				break;
        			}
        			q.push({{i,y},d+1});
        			it=row[i].erase(it);
        			col[y].erase(col[y].find(i));
        		}
        		else{
        			break;
        		}
        	}
        	it=col[j].lower_bound(i);
        	while(1){
        		if(sz(col[j])==0){
        			break;
        		}
        		if(it==col[j].end()){
        			it--;
        		}
        		int y=*it;
        		int f=0;
        		if(it==col[j].begin()){
        			f=1;
        		}
        		if(y>=i){
        			if(f)break;
        			it--;continue;
        		}
        		if(y<=(i)&&y>=(i-k)){
        			if(a[y][j]!='.'){
        				break;
        			}
        			q.push({{y,j},d+1});
        			if(f){
        				col[j].erase(it);
        				row[y].erase(row[y].find(j));
        				break;
        			}
        			col[j].erase(it--);
        			row[y].erase(row[y].find(j));
        		}
        		else{
        			break;
        		}
        	}
        	it=col[j].lower_bound(i);
        	while(it!=col[j].end()){
        		int y=*it;
        		if(y<=(i+k)&&y>=(i)){
        			if(a[y][j]!='.'){
        				break;
        			}
        			q.push({{y,j},d+1});
        			it=col[j].erase(it);
        			row[y].erase(row[y].find(j));
        		}
        		else{
        			break;
        		}
        	}
        }
        cout<<ans[x2][y2];
    }   
    timecalculater();
    return 0;   
} 

Measured memory_bytes: 149172