1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
#include <bits/stdc++.h>
using namespace std;

#define pll pair<long long, long long>
#define pii pair<int,int>
#define px first
#define py second
#define ll long long
#define eb emplace_back
#define vc vector

struct _debugger{
    void LGdebug(vector<vector<ll>> &g){
        cout << "GRAPH IS:\n";
        for(unsigned ll i=0; i<g.size(); i++){
            cout << i <<": ";
            for(auto c: g[i]) cout << c << " ";
            cout << "\n";
        }
        cout << "----------\n";
    }
    void LWGdebug(vector<vector<pll>> &g){
        cout << "WEIGHTED GRAPH IS:\n";
        for(unsigned ll i=0; i<g.size(); i++){
            cout << i <<": ";
            for(auto c: g[i]) cout << "{x: " << c.px << ", y: " << c.py << "} ";
            cout << "\n";
        }
        cout << "----------\n";
    }
    void LVdebug(vector<ll> &v ){
        cout << "VECTOR IS: " << "\n";
        for(unsigned ll i=0; i<v.size(); i++) cout << i << ": " << v[i] << "\n";
        cout << "---------\n";
    }
    void Gdebug(vector<vector<int>> &g){
        cout << "GRAPH IS:\n";
        for(unsigned ll i=0; i<g.size(); i++){
            cout << i <<": ";
            for(auto c: g[i]) cout << c << " ";
            cout << "\n";
        }
        cout << "----------\n";
    }
    void WGdebug(vector<vector<pii>> &g){
        cout << "WEIGHTED GRAPH IS:\n";
        for(unsigned ll i=0; i<g.size(); i++){
            cout << i <<": ";
            for(auto c: g[i]) cout << "{x: " << c.px << ", y: " << c.py << "} ";
            cout << "\n";
        }
        cout << "----------\n";
    }
    void Vdebug(vector<int> &v ){
        cout << "VECTOR IS: " << "\n";
        for(unsigned ll i=0; i<v.size(); i++) cout << i << ": " << v[i] << "\n";
        cout << "---------\n";
    }
    void VPdebug(vector<pii> &v ){
        cout << "VECTOR IS: " << "\n";
        for(unsigned ll i=0; i<v.size(); i++) cout << i <<": " << "{x: " << v[i].px << ", y: " << v[i].py << "} \n";
        cout << "---------\n";
    }
};

_debugger deBug;
const ll linf = 4e18;   
const int inf = 1e9;
const int NN = 1e5+67;

void solve(){
  

  int n, k;
  cin >> n >> k;
  
  vc<int> tab(n+1,0);
  vc<bool> fixed(n+1, 0);
  ll res = 0;
  
  for(int i=1; i<=n; i++) cin >> tab[i];
  
  for(int use = 1; use <=n; use++){
    int candidate = 0;
    
    for(int i=1; i<=n; i++){
      if(tab[i]>tab[candidate] && fixed[i]==false){
        candidate = i;
      }
    }
    if(candidate==0)break;
    //cout << candidate << " ";
    fixed[candidate] = true;
    if(candidate+1 <= n){
      res += max(0, tab[candidate]-k - tab[candidate+1]);
      tab[candidate+1] = max(tab[candidate]-k, tab[candidate+1]);
    }
    if(candidate-1 > 0){
      res += max(0, tab[candidate]-k - tab[candidate-1]);
      tab[candidate-1] = max(tab[candidate]-k, tab[candidate-1]);
    }
  }
  
  // for(int i=1; i<=n; i++){
  //   cout << tab[i] << " ";
  // } cout << endl;
  
  cout << res;

  
  
  
}




signed main(){
    cin.tie(0) -> sync_with_stdio(0);
    //int t; cin >> t; 
    //while(t--)
        solve();
    return 0;
}