POLE

#include <bits/stdc++.h>
#define task ""
#define pb push_back
#define ld long double
#define ll long long
#define ull unsigned long long

using namespace std;

int typetest;

inline void fastIOfileinput(){
    ios_base:: sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    if(fopen(task".inp", "r")){
        freopen(task".inp", "r", stdin);
        freopen(task".out", "w", stdout);
    }
    if(fopen(task".in", "r")){
        freopen(task".in", "r", stdin);
        freopen(task".out", "w", stdout);
    }
    typetest = 0;
}

ll l[10009][1009], h[10009][1009];
int n;
ll a[10009], m;
ll f[10009][1009];
ll c;

inline void Enter(){
    cin >> n >> c;
    for(int i = 1; i <= n; ++i){
        cin >> a[i];
        m = max(m, a[i]);
    }
    memset(f, 0, sizeof(f));
    for(int i = 1; i <= n; ++i){
        h[i][m + 1] = INT_MAX;
        l[i][0] = INT_MAX;
    }
}
inline void solve(){
    for(int i = 1; i <= n; ++i){
        for(ll j = 1; j <= m; ++j){
            if(j >= a[i]){
                f[i][j] = (ll) (i != 1) * min(l[i - 1][j] + c * j, h[i - 1][j] - c * j) + (j - a[i]) * (j - a[i]);
                l[i][j] = min(l[i][j - 1], f[i][j] - c * j);
            }
            else{
                f[i][j] = l[i][j] = INT_MAX;
            }
            if(m - j + 1 >= a[i]){
            f[i][m - j + 1] = (ll)(i != 1) * min(l[i - 1][m - j + 1] + c * (m - j + 1),
                                  h[i - 1][m - j + 1] - c * (m - j + 1)) + (m - j + 1LL - a[i]) * (m - j + 1LL - a[i]);
            h[i][m - j + 1] = min(h[i][m - j + 2], f[i][m - j + 1] + c * (m - j + 1));
            }
            else{
                h[i][m - j + 1] = h[i][m - j + 2];
            }
        }
    }
    ll ans = 1e18;
    for(int i = 1; i <= m; ++i){
        ans = min(ans, f[n][i]);
    }
    cout << ans;
}

int main(){
    fastIOfileinput();
    if(typetest){
        int t;
        cin >> t;
        while(t--){
            Enter();
            solve();
        }
    }
    else{
        Enter();
        solve();
    }
}