#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#define rep(i,n) for (int i=1;i<=n;i++)
#define fr(i,s,e) for (int i=s;i<=e;i++)
#define INF 0x3f3f3f3f

using namespace std;

const int N=10005;
int n,m,a,b,la,lb,p[N],f[2][N];

void init()
{
    scanf("%d%d",&n,&m);
    rep(i,n) scanf("%d",&p[i-1]);
}

void dawn()
{
    memset(f,0x3f,sizeof(f));
    la=m/(n-1);lb=la+1;
    b=m%(n-1);a=n-1-b;
    f[0][0]=p[0];
    fr(i,0,n-2)
    {
        int ii=i&1;
        fr(i,max(0,i+1-b),min(i+1,a)) f[1-ii][i]=INF;
        fr(j,max(0,i-b),min(i,a)) if (f[ii][j]!=INF)
        {
            int t=j*la+(i-j)*lb;
            f[1-ii][j]=min(f[1-ii][j],f[ii][j]+abs(p[i+1]-(t+lb)));
            f[1-ii][j+1]=min(f[1-ii][j+1],f[ii][j]+abs(p[i+1]-(t+la)));
        }
    }
    printf("%d\n",f[(n-1)&1][a]);
}

int main()
{
    //freopen("1.txt","r",stdin);
    init();
    dawn();
}