#include <stdlib.h>
#include <stdio.h>
#include <limits.h>

#define SIZE 5000

long long recurses=0;

/* the table holds the minimum cost of making the sum at i be S */
int table[SIZE][SIZE]; /* [i][S] */

/* Find cost of changing A[i], A[i+K], A[i+2K],... to S. */
int immediate_cost(int *A,int N,int K, int i, int x)
{ int cost=0, j;
  for(j=i;j<N;j+=K)
    if(A[j] != x)
      cost++;
  return cost;
}  

/* minimum cost of making the sum at i be S is the cost of changing
   i to x + cost of making the sum previous to i be S-x */
int mincost(int *A,int N,int K, int i, int S)
{
  int cost,currcost,x;

  /* if it is in the table, just return the table value */
  if((cost = table[i][S]) > -1)
    return cost;
  
  if(i == 0)  /* First element in the array. */
    {
      cost = immediate_cost(A,N,K,i,S);
      table[i][S]=cost;       // put it in the table
      return cost;
    }

  // find minimum cost of changing elememnt i to 0..S
  cost = currcost = mincost(A,N,K,i-1,S) + immediate_cost(A,N,K,i,0);
  for(x = 1;x<=S;x++)
    {
      recurses++;
      currcost = mincost(A,N,K,i-1,S-x) + immediate_cost(A,N,K,i,x);
      if(currcost < cost)
	cost = currcost;
    }
  table[i][S]=cost; // enter value into table
  return cost;
}

// Find pattern of length K which is S smooth, and will cause 
// the least number of changes when applied to entire array.
int main()
{
  static int A[SIZE];
  int N,K,S,i,j,k,cost;

  if(scanf("%d%d%d",&N,&K,&S)!=3)
    {
      perror("unable to read N K S: ");
      exit(1);
    }
  
  for(i=0;i<N;i++)
    if(scanf("%d",A+i)!=1)
      {
	perror("unable to read array element: ");
	exit(2);
      }

  // initialize the table elements that we will need
  for(i=0;i<K;i++)
    for(j=0;j<=S;j++)
      table[i][j] = -1;

  cost = mincost(A,N,K,K-1,S);
      
  printf("%d\n",cost);
  //  printf("%lld\n",recurses);
  
  return 0;
}