using System;
using System.Linq;
using System.Collections.Generic;

namespace Contest
{
  class Program
  {
    static void Main(string[] args)
    {
      ABC170.F();
    }
    class ABC170
    {
      public static void A()
      {
        var X = Read.IntN().ToList();
        Console.WriteLine(X.IndexOf(0) + 1);
      }
      public static void B()
      {
        var X = Read.Int();
        var Y = Read.Int();
        Console.WriteLine(X * 2 <= Y && Y <= 4 * X && Y % 2 == 0 ? "Yes" : "No");
      }
      public static void C()
      {
        var X = Read.Int();
        var N = Read.Int();
        var P = new int[0];
        if (N > 0)
        {
          P = Read.IntN();
        }
        var Y = 99999;
        for(int i = -100; i <= 200; ++i)
        {
          if(!P.Contains(i) && Math.Abs(X - Y) > Math.Abs(X - i))
          {
            Y = i;
          }
        }
        Console.WriteLine(Y);
      }
      public static void D()
      {
        var N = Read.Int();
        var A = Read.IntN();
        var freq = Util.Frequency(A);
        var below1000 = new HashSet<int>();
        foreach(var kvp in freq)
        {
          if (kvp.Key <= 1000)
          {
            below1000.Add(kvp.Key);
          }
        }
        int count = 0;
        foreach(var a in A)
        {
          bool ok = true;
          foreach(var b in below1000)
          {
            if (a % b == 0)
            {
              if (a != b || freq[a] > 1)
              {
                ok = false;
                break;
              }
            }
          }
          if (!ok) { continue; }
          for(int i = 1; i <= 1000; ++i)
          {
            if (a % i == 0)
            {
              var d = a / i;
              if (freq.ContainsKey(d) && (i > 1 || freq[d] > 1))
              {
                ok = false;
                break;
              }
            }
          }
          if (ok) { count++; }
        }
        Console.WriteLine(count);
      }
      public static void E()
      {
        var N = Read.Int();
        var Q = Read.Int();
        var AB = Read.TupleInt(N);
        var CD = Read.TupleInt(Q);
        var count = new int[200001];
        var belong = new int[200001];
        var sets = new Util.MultiSet<int>[200001];
        for(int i = 0; i < sets.Length; ++i)
        {
          sets[i] = new Util.MultiSet<int>();
        }
        for(int i=0;i<N;++i)
        {
          var A = AB[i].Item1;
          var B = AB[i].Item2;
          count[B]++;
          belong[i] = B;
          sets[B].Insert(A);
        }
        var highest = new Util.MultiSet<int>();
        for(int i = 1; i < count.Length; ++i)
        {
          if (count[i] > 0)
          {
            highest.Insert(sets[i].ElementAt(count[i] - 1));
          }
        }
        var ans = new List<int>();
        foreach(var cd in CD)
        {
          var C = cd.Item1;
          var D = cd.Item2;
          var a = AB[C - 1].Item1;
          var b = belong[C - 1];
          var hc1 = sets[b].ElementAt(count[b] - 1);
          count[b]--;
          sets[b].Remove(a);
          if (count[b] == 0)
          {
            highest.Remove(a);
          }
          else
          {
            if (a == hc1)
            {
              var newh = sets[b].ElementAt(count[b] - 1);
              if (hc1 != newh)
              {
                highest.Remove(hc1);
                highest.Insert(newh);
              }
            }
          }
          var hc2 = count[D] == 0 ? 0 : sets[D].ElementAt(count[D] - 1);
          count[D]++;
          belong[C - 1] = D;
          sets[D].Insert(a);
          if (count[D] == 1)
          {
            highest.Insert(a);
          }
          else
          {
            var newh = sets[D].ElementAt(count[D] - 1);
            if (hc2 != newh)
            {
              highest.Remove(hc2);
              highest.Insert(newh);
            }
          }
          ans.Add(highest.ElementAt(0));
        }
        Console.WriteLine(String.Join(Environment.NewLine, ans));
      }
      public static void F()
      {
        var H = Read.Int();
        var W = Read.Int();
        var K = Read.Int();
        var X1 = Read.Int();
        var Y1 = Read.Int();
        var X2 = Read.Int();
        var Y2 = Read.Int();
        var C = Enumerable.Range(0, H).Select(i => Read.Str()).ToArray();
        var board = new bool[H + 2, W + 2];
        for(int i = 0; i < H; ++i)
        {
          for (int j = 0; j < W; ++j)
          {
            if (C[i][j] == '.')
            {
              board[i + 1, j + 1] = true;
            }
          }
        }
        var dx = new int[] { 1, -1, 0, 0 };
        var dy = new int[] { 0, 0, 1, -1 };
        var dist = Util.Gen(H + 2, W + 2, -1);
        var nextDist = Enumerable.Range(0, 4).Select(i => Util.Gen(H + 2, W + 2, -1)).ToArray();
        dist[X1, Y1] = 0;
        var queue = new Queue<Tuple<int, int>>();
        queue.Enqueue(new Tuple<int, int>(X1, Y1));
        while (queue.Count > 0)
        {
          var t = queue.Dequeue();
          for(int i = 0; i < 4; ++i)
          {
            for (int j = 1; j <= K; ++j)
            {
              var X = t.Item1 + dx[i] * j;
              var Y = t.Item2 + dy[i] * j;
              if(board[X,Y] && dist[X, Y] < 0)
              {
                dist[X, Y] = dist[t.Item1, t.Item2] + 1;
                nextDist[i][X,Y] = dist[t.Item1, t.Item2] + 1;
                queue.Enqueue(new Tuple<int, int>(X, Y));
              }
              else
              {
                if (!board[X, Y] || dist[X, Y] <= dist[t.Item1, t.Item2] || nextDist[i][X, Y] == dist[t.Item1, t.Item2] + 1)
                {
                  break;
                }
              }
            }
          }
        }
        Console.WriteLine(dist[X2, Y2]);
      }
    }

    class Util
    {
      public static T[,] Gen<T>(int r, int c, T v)
      {
        var matrix = new T[r, c];
        for (int i = 0; i < r; ++i)
        {
          for (int j = 0; j < c; ++j)
          {
            matrix[i, j] = v;
          }
        }
        return matrix;
      }
      public static long[] ASum(long[] array)
      {
        var res = new long[array.Length + 1];
        for (int i = 0; i < array.Length; ++i)
        {
          res[i + 1] = res[i] + array[i];
        }
        return res;
      }
      public static long[,] ASum(long[,] matrix)
      {
        var N = matrix.GetLength(0);
        var M = matrix.GetLength(1);
        var res = new long[N + 1, M + 1];
        for(int i = 0; i < N; ++i)
        {
          for(int j = 0; j < M; ++j)
          {
            res[i + 1, j + 1] = res[i, j + 1] + res[i + 1, j] - res[i, j] + matrix[i, j];
          }
        }
        return res;
      }
      public static Dictionary<T, long> Frequency<T>(T[] array)
      {
        var dict = new Dictionary<T, long>();
        foreach (var a in array)
        {
          if (!dict.ContainsKey(a)) { dict.Add(a, 0); }
          dict[a]++;
        }
        return dict;
      }
      public static HashSet<long> Divisor(long x)
      {
        var div = new HashSet<long>(); for (long p = 1; p * p <= x; ++p) { if (x % p == 0) { div.Add(p); } }
        foreach (var d in div.ToArray())
        {
          if (!div.Contains(x / d)) { div.Add(x / d); }
        }
        return div;
      }
      public class BST<T> where T : IComparable
      {
        public class Node
        {
          public T V;
          public Node L, R;
          public int Count;
          public Node(T v) { V = v; Count = 1; }
        }
        static Random _rnd = new Random();
        public static int Count(Node t) { return t == null ? 0 : t.Count; }
        static Node Update(Node t) { t.Count = Count(t.L) + Count(t.R) + 1; return t; }
        public static Node Merge(Node l, Node r)
        {
          if (l == null || r == null) return l == null ? r : l;
          if ((double)Count(l) / (double)(Count(l) + Count(r)) > _rnd.NextDouble())
          { l.R = Merge(l.R, r); return Update(l); }
          else { r.L = Merge(l, r.L); return Update(r); }
        }
        public static Tuple<Node, Node> Split(Node t, int k)
        {
          if (t == null) return new Tuple<Node, Node>(null, null);
          if (k <= Count(t.L))
          {
            var s = Split(t.L, k);
            t.L = s.Item2;
            return new Tuple<Node, Node>(s.Item1, Update(t));
          }
          else
          {
            var s = Split(t.R, k - Count(t.L) - 1);
            t.R = s.Item1;
            return new Tuple<Node, Node>(Update(t), s.Item2);
          }
        }
        public static Node Remove(Node t, T v)
        {
          if (Find(t, v) == null) return t;
          return RemoveAt(t, LowerBound(t, v));
        }
        public static Node RemoveAt(Node t, int k)
        {
          var s = Split(t, k);
          var s2 = Split(s.Item2, 1);
          return Merge(s.Item1, s2.Item2);
        }
        public static bool Contains(Node t, T v) { return Find(t, v) != null; }
        public static Node Find(Node t, T v)
        {
          while (t != null)
          {
            var cmp = t.V.CompareTo(v);
            if (cmp > 0) t = t.L;
            else if (cmp < 0) t = t.R;
            else break;
          }
          return t;
        }

        public static Node FindByIndex(Node t, int idx)
        {
          if (t == null) return null;
          var currentIdx = Count(t) - Count(t.R) - 1;
          while (t != null)
          {
            if (currentIdx == idx) return t;
            if (currentIdx > idx)
            { t = t.L; currentIdx -= (Count(t == null ? null : t.R) + 1); }
            else { t = t.R; currentIdx += (Count(t == null ? null : t.L) + 1); }
          }
          return null;
        }
        public static int UpperBound(Node t, T v)
        {
          var torg = t;
          if (t == null) return -1;

          var ret = Int32.MaxValue;
          var idx = Count(t) - Count(t.R) - 1;
          while (t != null)
          {
            var cmp = t.V.CompareTo(v);

            if (cmp > 0)
            {
              ret = Math.Min(ret, idx);
              t = t.L;
              idx -= (Count(t == null ? null : t.R) + 1);
            }
            else if (cmp <= 0)
            {
              t = t.R;
              idx += (Count(t == null ? null : t.L) + 1);
            }
          }
          return ret == Int32.MaxValue ? Count(torg) : ret;
        }
        public static int LowerBound(Node t, T v)
        {
          var torg = t;
          if (t == null) return -1;

          var idx = Count(t) - Count(t.R) - 1;
          var ret = Int32.MaxValue;
          while (t != null)
          {
            var cmp = t.V.CompareTo(v);
            if (cmp >= 0)
            {
              if (cmp == 0) ret = Math.Min(ret, idx);
              t = t.L;
              if (t == null) ret = Math.Min(ret, idx);
              idx -= t == null ? 0 : (Count(t.R) + 1);
            }
            else if (cmp < 0)
            {
              t = t.R;
              idx += (Count(t == null ? null : t.L) + 1);
              if (t == null) return idx;
            }
          }
          return ret == Int32.MaxValue ? Count(torg) : ret;
        }
        public static Node Insert(Node t, T v)
        {
          var ub = LowerBound(t, v);
          return InsertByIdx(t, ub, v);
        }
        static Node InsertByIdx(Node t, int k, T v)
        {
          var s = Split(t, k);
          return Merge(Merge(s.Item1, new Node(v)), s.Item2);
        }
        public static IEnumerable<T> Enumerate(Node t)
        {
          var ret = new List<T>();
          Enumerate(t, ret);
          return ret;
        }
        static void Enumerate(Node t, List<T> ret)
        {
          if (t == null) return;
          Enumerate(t.L, ret);
          ret.Add(t.V);
          Enumerate(t.R, ret);
        }
      }
      public class Set<T> where T : IComparable
      {
        protected BST<T>.Node _root;
        public T this[int idx] { get { return ElementAt(idx); } }
        public int Count() { return BST<T>.Count(_root); }
        public virtual void Insert(T v)
        {
          if (_root == null) _root = new BST<T>.Node(v);
          else
          {
            if (BST<T>.Find(_root, v) != null) return;
            _root = BST<T>.Insert(_root, v);
          }
        }
        public void Clear() { _root = null; }
        public void Remove(T v) { _root = BST<T>.Remove(_root, v); }
        public bool Contains(T v) { return BST<T>.Contains(_root, v); }
        public T ElementAt(int k)
        {
          var node = BST<T>.FindByIndex(_root, k);
          if (node == null) throw new IndexOutOfRangeException();
          return node.V;
        }
        public int Count(T v) { return BST<T>.UpperBound(_root, v) - BST<T>.LowerBound(_root, v); }
        public int LowerBound(T v) { return BST<T>.LowerBound(_root, v); }
        public int UpperBound(T v) { return BST<T>.UpperBound(_root, v); }
        public Tuple<int, int> EqualRange(T v)
        {
          if (!Contains(v)) return new Tuple<int, int>(-1, -1);
          return new Tuple<int, int>(BST<T>.LowerBound(_root, v), BST<T>.UpperBound(_root, v) - 1);
        }
        public List<T> ToList() { return new List<T>(BST<T>.Enumerate(_root)); }
      }
      public class MultiSet<T> : Set<T> where T : IComparable { public override void Insert(T v) { if (_root == null) { _root = new BST<T>.Node(v); } else { _root = BST<T>.Insert(_root, v); } } }
    }
    class Bound
    {
      public static int Lowerbound<T1, T2>(SortedList<T1, T2> list, T1 x) where T1 : IComparable<T1>
      {
        return Lowerbound(list.Keys, x);
      }
      public static int Upperbound<T1, T2>(SortedList<T1, T2> list, T1 x) where T1 : IComparable<T1>
      {
        return Upperbound(list.Keys, x);
      }
      public static int Lowerbound<T>(IList<T> list, T x) where T : IComparable<T>
      {
        int min = 0;
        int max = list.Count;
        while (min < max)
        {
          var mid = (min + max) / 2;
          if (list[mid].CompareTo(x) >= 0)
          {
            max = mid;
          }
          else
          {
            min = mid + 1;
          }
        }
        return max;
      }
      public static int Upperbound<T>(IList<T> list, T x) where T : IComparable<T>
      {
        int min = 0;
        int max = list.Count;
        while (min < max)
        {
          var mid = (min + max) / 2;
          if (list[mid].CompareTo(x) > 0)
          {
            max = mid;
          }
          else
          {
            min = mid + 1;
          }
        }
        return max;
      }
      public static int UpperboundInt(List<int> list, int x)
      {
        int min = 0;
        int max = list.Count;
        while (min < max)
        {
          var mid = (min + max) / 2;
          if (list[mid] > x)
          {
            max = mid;
          }
          else
          {
            min = mid + 1;
          }
        }
        return max;
      }
    }

    static class Read
{
static Queue<string> queue = new Queue<string>();
static void Enqueue() { var ss = Console.ReadLine().Split(' '); foreach (var s in ss) { queue.Enqueue(s); } }
public static int Int() { if (queue.Count == 0) { Enqueue(); } return Convert.ToInt32(queue.Dequeue()); }
public static long Long() { if (queue.Count == 0) { Enqueue(); } return Convert.ToInt64(queue.Dequeue()); }
public static string Str() { if (queue.Count == 0) { Enqueue(); } return queue.Dequeue(); }
public static int[] IntN() { return Console.ReadLine().Split(' ').Select(s => Convert.ToInt32(s)).ToArray(); }
public static long[] LongN() { return Console.ReadLine().Split(' ').Select(s => Convert.ToInt64(s)).ToArray(); }
public static ulong[] ULongN() { return Console.ReadLine().Split(' ').Select(s => Convert.ToUInt64(s)).ToArray(); }
public static string[] StrN() { return Console.ReadLine().Split(' '); }
public static Tuple<int, int>[] TupleInt(int n) { List<Tuple<int, int>> list = new List<Tuple<int, int>>(); for (int i = 0; i < n; ++i) { var ab = Read.IntN(); list.Add(new Tuple<int, int>(ab[0], ab[1])); } return list.ToArray(); }
public static Tuple<long, long>[] TupleLong(int n) { List<Tuple<long, long>> list = new List<Tuple<long, long>>(); for (int i = 0; i < n; ++i) { var ab = Read.LongN(); list.Add(new Tuple<long, long>(ab[0], ab[1])); } return list.ToArray(); }
public static Tuple<string, string>[] TupleStr(int n) { List<Tuple<string, string>> list = new List<Tuple<string, string>>(); for (int i = 0; i < n; ++i) { var ab = Read.StrN(); list.Add(new Tuple<string, string>(ab[0], ab[1])); } return list.ToArray(); }
public static Tuple<double, double>[] TupleDouble(int n) { List<Tuple<double, double>> list = new List<Tuple<double, double>>(); for (int i = 0; i < n; ++i) { var ab = Read.LongN(); list.Add(new Tuple<double, double>(ab[0], ab[1])); } return list.ToArray(); }
public static long[,] LongMatrix(int r, int c) { var mat = new long[r, c]; for (int i = 0; i < r; ++i) { var x = Read.LongN(); for (int j = 0; j < c; ++j) { mat[i, j] = x[j]; } } return mat; }
public static Dictionary<int, HashSet<int>> AdjacencyList(int N, int M, bool isDirectional = false)
{
Dictionary<int, HashSet<int>> dict = new Dictionary<int, HashSet<int>>();
for (int i = 0; i <= N; ++i) { dict.Add(i, new HashSet<int>()); }
        for (int i = 0; i < M; ++i) { var ab = Read.IntN(); if (!dict[ab[0]].Contains(ab[1])) { dict[ab[0]].Add(ab[1]); } if (!isDirectional && !dict[ab[1]].Contains(ab[0])) { dict[ab[1]].Add(ab[0]); } }
        return dict;
}
public static Dictionary<int, Dictionary<int, long>> AdjacencyListWithWeight(int N, int M)
{
Dictionary<int, Dictionary<int, long>> dict = new Dictionary<int, Dictionary<int, long>>(); for (int i = 0; i <= N; ++i) { dict.Add(i, new Dictionary<int, long>()); }
for (int i = 0; i < M; ++i) { var ab = Read.IntN(); dict[ab[0]].Add(ab[1], ab[2]); dict[ab[1]].Add(ab[0], ab[2]); }
return dict;
}
}
    }
}


Measured memory_bytes: 84400