#include<bits/stdc++.h>
using namespace std;

#define endl "\n"
#define LL long long
#define ULL unsigned long long
const LL        INF = 1LL<<59;
const double    PI = 2.0 * acos(0.0);

typedef pair<int,int> pii;
typedef pair<LL,LL> pll;
typedef vector<int> vi;
typedef vector<LL> vl;
typedef vector<pii> vii;
typedef vector<pll> vll;


//// Including Policy Based DS
//#include <ext/pb_ds/assoc_container.hpp>
//#include <ext/pb_ds/tree_policy.hpp>
//using namespace __gnu_pbds;
//
/////cout<<*X.find_by_order(1)<<endl;
/////cout<<X.order_of_key(-5)<<endl;
//
//typedef tree<
//int,
//null_type,
//less< int >,
//rb_tree_tag,
//tree_order_statistics_node_update>
//ordered_set;

#define READ        freopen("in.txt","r",stdin)
#define WRITE       freopen("out.txt","w",stdout)
#define BOOST		ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0)
#define sf 			scanf
#define pf 			printf
#define F  			first
#define S  			second
#define pb 			push_back
#define NL			pf("\n")
#define ALL(v)		v.begin(),v.end()
#define si(x)		sf("%d",&x);
#define sii(x,y)	sf("%d%d",&x,&y);
#define siii(x,y,z)	sf("%d%d%d",&x,&y,&z);
#define sl(x)		sf("%lld",&x);
#define sll(x,y)	sf("%lld%lld",&x,&y);
#define slll(x,y,z)	sf("%lld%lld%lld",&x,&y,&z);
#define sqr(x)      ( (x) * (x) )
#define mem(x,y) 	memset(x,y,sizeof x )
#define ch 			printf("Came Here!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!\n")
#define deb(x)      cerr<<#x<<" === "<<x<<"\n"
#define SV(v)		sort(v.begin(),v.end())
#define SVR(v,cmp)	sort(v.begin(),v.end(),cmp)
#define FOR(i,n)	for(int i=0;i<n;i++)
#define cnd			tree[idx]
#define lc			tree[idx*2]
#define rc			tree[idx*2+1]
#define lnd 		(2*idx),(b),( (b+e) /2 )
#define rnd 		((2*idx)+1),(((b+e)/2)+1),(e)

// graph direction array [4]
int X[4]={0,0,-1,1};
int Y[4]={1,-1,0,0};
// graph direction array [8]
//int X[8]={0,0,1,-1,-1,1,1,-1};
//int Y[8]={1,-1,0,0,-1,-1,1,1};
// Bishop direction array [8]
//int X[8]={0,0,1,-1,-1,1,1,-1};
//int Y[8]={1,-1,0,0,-1,-1,1,1};
// Knight Direction Array
//int KX[8] = {1,1,2,2,-1,-1,-2,-2};
//int KY[8] = {2,-2,1,-1,2,-2,1,-1};

// Bit Operations
#define popcountL   __builtin_popcountll
#define popcount    __builtin_popcount
inline bool checkBit(int N,int pos){return (bool)(N & (1<<pos));} // check bit
inline int setBit(int N,int pos){	return N=N | (1<<pos);}// set bit
inline int unsetBit(int N,int pos){	return N=( N & ( ~( 1<<pos ) ) );}// unset bit
inline int toggleBit(int N,int pos){ return N = ( N ^(1<<pos) ); }// toggle bit


inline LL modMul(LL a, LL b,LL mod){
    LL ans = 0;
    a = a % mod;
    while (b > 0){
        if ( b % 2 )ans = (ans%mod+ a%mod) % mod;
        a = (a%mod * 2%mod) % mod;
        b /= 2;
    }
    return ans % mod;
}
inline LL powerMod(LL a,LL b,LL mod){
	if(b==0)return 1LL%mod;
	LL x=powerMod( a,b/2,mod );
	x = ( x%mod * x%mod ) % mod;
	if( b%2==1 )x = ( x%mod * a%mod ) % mod;
	return x%mod;
}
inline LL lcm( LL a,LL b ){
	LL g = __gcd(a,b);
	return ((a/g) * b);
}

//-------------------------------------------------------------------------------
//-------------------------------------------------------------------------------
const int mx = 2e5+50;


struct node{
    int r=0,c=0,pdir=0,d=0;
    LL cost = 0;
    node(){}
    node(int x,int y,int p,int dd,int cc){
        r = x,c = y,pdir = p;
        d = dd;cost = cc;
    }
};
bool operator<(node a, node b){
    return a.cost > b.cost;
}


const int inf = 2e8;

struct br{
    vector<bool> vis;
    vector<LL> dis;
    br(){
        vis = vector<bool>(5,0);
        dis = vector<LL>(5);
        FOR(i,5)dis[i] = INF;
    }
};

int main(){
    BOOST;
    #ifdef MujahidPC
        double start = clock();
    //    READ;
    //    WRITE;
    #endif
    int t,n,m,k;
    int si,sj,di,dj;

    cin>>n>>m>>k;
    cin>>si>>sj>>di>>dj;
    si--,sj--,di--,dj--;

    vector<string> grid;
    vector< vector<br> > data( n+1,vector<br>(m+1) );
    FOR(i,n){
        string row;
        cin>>row;
        grid.pb(row);
    }


    LL ans = INF;
    priority_queue<node> Q;
    Q.push( node(si,sj,0,0,0) );
    data[si][sj].dis[0] = 0;

    while(!Q.empty()){

        node cur = Q.top();Q.pop();
        if( cur.r==di && cur.c==dj ){
            ans = cur.cost;
            break;
        }
        FOR(i,4){
            int nr = cur.r+X[i];
            int nc = cur.c+Y[i];
            int pd = cur.pdir;
            int cd = i+1;
            if( nr>=0 && nr<n && nc>=0 && nc<m && grid[nr][nc]!='@' ){
                int newcost = 0;
                int newd = 0;
                if( pd==cd ){
                    if( cur.d<k ){
                        newd = cur.d + 1;
                    }
                    else {
                        newcost = 1;
                        newd = 1;
                    }
                }
                else{
                    newd = 1;
                    newcost = 1;
                }
                if( data[nr][nc].dis[cd] > cur.cost+newcost ){
                    data[nr][nc].dis[cd] = cur.cost+newcost;
                    Q.push(node(nr,nc,cd,newd,cur.cost+newcost));
                }
            }
        }
    }
    if( ans>=INF )ans = -1;
    cout<<ans<<endl;

    #ifdef MujahidPC
        double tim = (clock() - start)/CLOCKS_PER_SEC;
        cerr<<"Running Time : "<<tim<<" \n";
    #endif
    return 0;
}


Measured memory_bytes: 425064