#include <bits/stdc++.h>
#define all(x) x.begin(), x.end()
#define sz(x) (int) x.size()
#define endl '\n'
#define pb push_back
#define _ ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
using namespace std;
using ll = long long;
using ull = unsigned long long;
using ii = pair<int,int>;
using iii = tuple<int,int,int>;
const int inf = 2e9+1;
const int mod = 1e9+7;
const int maxn = 1e7+10;
template<typename X, typename Y> bool ckmin(X& x, const Y& y) { return (y < x) ? (x=y,1):0; }
template<typename X, typename Y> bool ckmax(X& x, const Y& y) { return (x < y) ? (x=y,1):0; }
ll R[maxn], L[maxn];
ll delivery(int n, int k, int l, int p[]){
int fi = (n-1)%k;
ll cur = 0;
for(int i=n-1;~i;--i){
if(i%k==fi){
cur += ll(2*(l - p[i]));
}else{
cur -= ll(l - p[i+1]);
cur += ll(p[i+1]-p[i]);
cur += ll(l - p[i]);
}
R[n-i] = cur;
}
cur = 0;
for(int i=0;i<n;++i){
if(i%k==0){
cur += ll(2*p[i]);
}else{
cur -= ll(p[i-1]);
cur += ll(p[i]-p[i-1]);
cur += ll(p[i]);
}
L[i+1] = cur;
}
ll resp = R[n];
for(int i=0;i<n;++i){
ckmin(resp, R[i] + L[n-i]);
}
for(int i=0;i<=n-k;++i){
ckmin(resp, R[i] + L[n-k-i] + ll(l));
}
return resp;
}
// int positions[maxn];
// int main(){
// int n,k,l;cin>>n>>k>>l;
// for(int i=0;i<n;++i)cin>>positions[i];
// cout<<delivery(n,k,l,positions)<<endl;
// }
