//clear adj and visited vector declared globally after each test case
//check for long long overflow
//while adding and subs check if mod becomes -ve
//while using an integer directly in a builtin function add ll
//Mod wale question mein last mein if dalo ie. Ans<0 then ans+=mod;
//Dont keep array name as size or any other key word

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
//#define int long long
#define IOS std::ios::sync_with_stdio(false); cin.tie(NULL);cout.tie(NULL);cout.precision(dbl::max_digits10);
#define pb push_back
#define mod 1000000007 //998244353
#define lld long double
#define mii map<int, int>
#define mci map<char, int>
#define msi map<string, int>
#define pii pair<int, int>
#define ff first
#define ss second
#define all(x) (x).begin(), (x).end()
#define rep(i,x,y) for(int i=x; i<y; i++)
#define fill(a,b) memset(a, b, sizeof(a))
#define vi vector<int>
#define setbits(x) __builtin_popcountll(x)
#define print2d(dp,n,m) for(int i=0;i<=n;i++){for(int j=0;j<=m;j++)cout<<dp[i][j]<<" ";cout<<"\n";}
typedef std::numeric_limits< double > dbl;
using namespace __gnu_pbds;
using namespace std;
typedef tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update> indexed_set;
const long long N=1000005, INF=(int)1e9;
lld pi=3.1415926535897932;
int dx[] = {1, -1, 0, 0};
int dy[] = {0, 0, 1, -1};
int lcm(int a, int b)
{
    int g=__gcd(a, b);
    return a/g*b;
}
int power(int a, int b, int p)
    {
        if(a==0)
        return 0;
        int res=1;
        a%=p;
        while(b>0)
        {
            if(b&1)
            res=(res*a)%p;
            b>>=1;
            a=(a*a)%p;
        }
        return res;
    }
string s[N];
int n,m,k;
bool check(int x, int y)
{
    if(x<0||y<0||x>=n||y>=m||s[x][y]=='@')
    return false;
    return true;
}
int32_t main()
{
    IOS;
    cin>>n>>m>>k;
    int x1,x2,y1,y2;
    cin>>x1>>y1>>x2>>y2;
    for(int i=0;i<n;i++)
    cin>>s[i];
    deque <pair <pii,pair<int, pii> > > q;//x, y, dir, dist(for k)
    x1--;y1--;x2--;y2--;
    q.push_back({{x1, y1}, {0, {0, 1}}});
    q.push_back({{x1, y1}, {1, {0, 1}}});
    q.push_back({{x1, y1}, {2, {0, 1}}});
    q.push_back({{x1, y1}, {3, {0, 1}}});
    int dp[n][m][4];
    rep(i,0,n)
    rep(j,0,m)
    rep(rr,0,4)
    dp[i][j][rr]=INF;
    dp[x1][y1][0]=1;dp[x1][y1][1]=1;dp[x1][y1][2]=1;dp[x1][y1][3]=1;
    while(!q.empty())
    {
        pair<pii, pair<int, pii> > p=q.front();
        q.pop_front();
        int x,y,dir,dist,cur;
        x=p.ff.ff;
        y=p.ff.ss;
        dir=p.ss.ff;
        dist=p.ss.ss.ff;
        cur=p.ss.ss.ss;
        //cout<<x<<" "<<y<<" "<<dir<<" "<<dist<<" "<<dp[x][y][dir]<<"\n";
        //cout<<x<<" "<<y<<" "<<dir<<" "<<dist<<"\n";
        for(int i=0;i<4;i++)
        {
            int xn=x+dx[i],yn=y+dy[i];
            if(check(xn, yn))
            {
                if(i==dir&&dist<k)
                {
                    if(dp[xn][yn][i]>cur)
                    q.push_front({{xn, yn}, {i, {dist+1, cur}}});
                    dp[xn][yn][i]=min(dp[xn][yn][i], cur);
                    //cout<<x<<" "<<y<<" "<<dir<<" "<<i<<" "<<xn<<' '<<yn<<'\n';
                }
                else
                {
                   //&&(dp[x][y][dir]<min({dp[xn][yn][0], dp[xn][yn][1], dp[xn][yn][2], dp[xn][yn][3]})))
                    if(dp[xn][yn][i]>(cur+1))
                    q.push_back({{xn, yn}, {i, {1, cur+1}}});
                    //if(xn==2&&yn==1&&i==1)
                    //cout<<x<<" "<<y<<" "<<dir<<" "<<dist<<" "<<dp[x][y][dir]<<"yo\n";
                    dp[xn][yn][i]=min(dp[xn][yn][i], cur+1);
                }
            }
        }
    }
    //cout<<dp[2][1][1]<<' '<<dp[1][1][1]<<"\n";
    /**for(int i=0;i<n;i++)
    {
        for(int j=0;j<m;j++)
        {
            cout<<dp[i][j][0]<<dp[i][j][1]<<" ";
        }
        cout<<"\n";
        for(int j=0;j<m;j++)
        {
            cout<<dp[i][j][2]<<dp[i][j][3]<<" ";
        }
        cout<<"\n\n";
    }**/
    int ans=INF;
    for(int i=0;i<4;i++)
    ans=min(ans, dp[x2][y2][i]);
    if(ans==INF)
    cout<<-1;
    else
    cout<<ans;
}


Measured memory_bytes: 56424