using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.IO;
using static System.Console;
using static System.Math;
 
public class Solve{
    static public int mod = 1000000007;
    static public string al = "abcdefghijklmnopqrstuvwxyz";
    public static void Main(){
        // 方針
        //
        var tn = inta();
        var t = tn[0];
        var y = tn[1];
        var del = tn[2];
        var map = new int[t,y+1];
        for(int i=0;i<t;i++){
            var a = rstr();
            for(int j=0;j<y;j++){
                map[i,j] = int.Parse(a[j].ToString());
            }
        }
        
        long ans = 0;
        
        //var tt = 3;
        //var ty = 1;
        for(int tate=0;tate<t;tate++){
            for(int yoko=0;yoko<y;yoko++){
                //WriteLine($"{tate} {yoko}");
                
                var tempmap = new int[t,y+1];
                for(int i=0;i<t;i++){
                    for(int j=0;j<y;j++){
                        tempmap[i,j] = map[i,j];
                    }
                }
                tempmap[tate,yoko] = 0;
                
                fall(ref tempmap,t,y);
                
                long score = 0;
                long multi = 1;
                while(delete(ref tempmap,del,t,y,ref score,ref multi)){
                    fall(ref tempmap,t,y);
                    /*
                    for(int i=0;i<t;i++){
                        for(int j=0;j<y;j++){
                            Write($"{tempmap[i,j]} ");
                        }
                        WriteLine();
                    }
                    WriteLine("-----------------------");
                    */
                }
                
                ans = Max(ans,score);
            }
        }
        WriteLine(ans);
	
	
    }
    static bool delete(ref int[,] map,int K,int t,int y,ref long score,ref long multi){
        var ret = false;
        long sum = 0;
        for(int i=0;i<t;i++){
            var num = -1;
            var count = 0;
            var dellist = new List<int>();
            for(int j=0;j<=y;j++){
                if(j == 0){
                    num = map[i,j];
                    count = 1;
                    dellist.Add(j);
                    continue;
                }
                if(map[i,j] != num || map[i,j] == 0){
                    //WriteLine($"{i} {j} {num} {count} {K} {sum} 2");
                    if(count >= K){
                        sum += num * count;
                        ret = true;
                        for(int d=0;d<dellist.Count;d++){
                            map[i,dellist[d]] = 0;
                        }
                    }
                    num = map[i,j];
                    count = 1;
                    dellist.Clear();
                    dellist.Add(j);
                }else if(map[i,j] == num){
                    //WriteLine($"{i} {j} {num} {count} {K} {sum} 1");
                    count++;
                    dellist.Add(j);
                }
                //WriteLine($"{i} {j} {num} {count} {K} {sum}");
            }
        }
        score += sum * multi;
        multi *= 2;
        return ret;
    }
    
    static void fall(ref int[,] map,int t,int y){
        for(int i=0;i<y;i++){
            var list = new List<int>();
            for(int j=t-1;j>=0;j--){
                if(map[j,i] > 0) list.Add(map[j,i]);
            }
            while(list.Count < t) list.Add(0);
            for(int j=t-1;j>=0;j--){
                map[j,i] = list[t-1-j];
            }
        }
    }
    
    public static void swap(ref int a,ref int b){int temp = a;a= b;b = temp;}
    static void charswap(ref char a,ref char b){char temp = a;a= b;b = temp;}
    static int ncr(int n,int r){if(n<r)return 0;r = Min(r,n-r);long nn = 1;for(int i=n-r+1;i<=n;i++){nn = nn*i%mod;}long rr = 1;for(int i=1;i<=r;i++){rr = rr*i%mod;}rr = square((int)rr,mod-2);nn = nn * rr %mod;return (int)nn;}
    // a^b mod
    static int square(int a,int b){string binary = Convert.ToString(b,2);int bileng = binary.Length;long a_power = a;long value = 1;for(int i=bileng-1;i>=0;i--){if(binary[i] == '1'){value = value*a_power%mod;}a_power = a_power*a_power%mod;}return (int)value;}
    static int square2(int a,int b){long output = 1;var list = new List<long>();int sh = 1;long n = a;list.Add(a);while(sh < b){sh *= 2;n = n*n%mod;list.Add(n);}for(int i=list.Count-1;i>=0;i--){if(b > sh){b -= sh;sh /= 2;output = output*list[i]%mod;}}return (int)output;}
    //各種読取
    static string rstr(){ return ReadLine(); }
    static int rint(){ return int.Parse(ReadLine()); }
    static long rlong(){ return long.Parse(ReadLine()); }
    static string[] stra(){ return ReadLine().Split(' '); }
    static char[] chara(){ string[] a=stra();string b="";for(int i=0;i<a.Length;i++){b+=a[i];}return b.ToCharArray();}
    static int[] inta(){ string[] read_str_array = ReadLine().Split(' '); int[] return_int_array = new int[read_str_array.Length]; for(int countup_i=0;countup_i<read_str_array.Length;countup_i++){ return_int_array[countup_i] = int.Parse(read_str_array[countup_i]); } return return_int_array; }
    static int[,] inta2(int num_array,int in_array){ int[,] int_array2 = new int[num_array,in_array]; for(int i=0;i<num_array;i++){ int[] temp_array = inta(); for(int j=0;j<in_array;j++){ int_array2[i,j] = temp_array[j]; } } return int_array2; }
    static long[] longa(){ string[] read_str_array = ReadLine().Split(' '); long[] return_long_array = new long[read_str_array.Length]; for(long countup_i=0;countup_i<read_str_array.Length;countup_i++){ return_long_array[countup_i] = long.Parse(read_str_array[countup_i]); } return return_long_array; }
    static double[] doublea(){ string[] read_str_array = ReadLine().Split(' '); double[] return_double_array = new double[read_str_array.Length]; for(long countup_i=0;countup_i<read_str_array.Length;countup_i++){ return_double_array[countup_i] = double.Parse(read_str_array[countup_i]); } return return_double_array; }
    // -----------------------------
    static long GCD(long a,long b){ if(a < b){ long temp = a; a = b; b = temp; } if(a % b == 0){ return b; } else{ long temp = b; b = a%b; a = temp; return GCD(a,b); } }
    static long LCM(long a,long b){ return a * b / GCD(a,b); }
    static void WriteArray(int[,] a,int b,int c){for(int i=0;i<b;i++){for(int j=0;j<c;j++){if(j!=0) Write(" ");Write(a[i,j]);}WriteLine();}}
}

Measured memory_bytes: 46168