#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define fo(i, n) for(ll i = 0; i<(n); i++)
#define F first
#define S second
#define pb push_back
#define deb(x) cout << #x << " = " << (x) << endl
#define deb2(x, y) cout << #x << " = " << (x) << ", " << #y << " = " << (y) << endl
typedef vector<ll> vl;
typedef vector<vl> vvl;
vl memo, p;
int n, k, l;
ll dp(ll pos){
if(pos == n) return 0;
ll &ans = memo[pos];
if(ans != -1) return ans;
ans = 1e18;
ll extra = min((-p[pos]+l)%l, (p[pos]+l)%l);
fo(i, k){
ll next = pos+i;
ans = min(ans, dp(next+1)+min((-p[next]+l)%l, (p[next]+l)%l)+extra);
if(i==k-1||next+1==n) break;
extra+=min((p[next]-p[next+1]+l)%l, (p[next+1]-p[next]+l)%l);
}
return ans;
}
long long delivery(int N, int K, int L, int P[]) {
n=N;k=K;l=L;
memo.assign(n+2, -1);
fo(i, n) p.pb(P[i]);
return dp(0);
}
