/*
UID:cheepok
PID:graze2
*/

#include<stdio.h>
#include<stdlib.h>
#define min(a,b) a<b?a:b

int n,m,tmp,a[1501],b[1501],f[1501][2501];

int abs(int k)
{return k>0?k:-k;}

int cmp(const void *a,const void *b)
{return *(int *)a-*(int *)b;}

int main()
{
	freopen("graze2.in","r",stdin);
	freopen("graze2.out","w",stdout);
	int i,j;scanf("%d%d",&n,&m);
	for(i=1;i<=n;i++)scanf("%d",&a[i]);
	qsort(a+1,n,4,cmp);
	tmp=m-(m-1)/(n-1)*(n-1)-1;
	m=(m-1)/(n-1);b[1]=1;
	for(i=2;i<=n;i++)b[i]=b[i-1]+m;
	f[1][0]=abs(a[1]-b[1]);
	for(i=1;i<=tmp;i++)f[1][i]=1000000001;
	for(i=2;i<=n;i++)
	{
		f[i][0]=f[i-1][0]+abs(a[i]-b[i]);
		for(j=1;j<=tmp;j++)
		{
			f[i][j]=min(f[i-1][j],f[i-1][j-1]);
			f[i][j]+=abs(a[i]-b[i]-j);
		}
	}
	printf("%d\n",f[n][tmp]);
	return 0;
}