ccpcf L. Paid Leave

模拟，:)

#include <bits/stdc++.h>
/*
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/hash_policy.hpp>
*/
using namespace std;

const double eps = 1e-10;
const double pi = 3.1415926535897932384626433832795;
const double eln = 2.718281828459045235360287471352;

#define f(i, a, b) for (int i = a; i <= b; i++)
#define scan(x) scanf("%d", &x)
#define mp make_pair
#define pb push_back
#define lowbit(x) (x&(-x))

#define fi first
#define se second
#define SZ(x) int((x).size())
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define summ(a) (accumulate(all(a), 0ll))

typedef unsigned long long ull;
typedef pair<int,int> pii;
typedef vector<int> vi;

using ll=long long;

ll n,m,x,y,a[(int)2e5+9],ans,lstd,lstw=-10086;

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    cin>>n>>m>>x>>y; 
    for(int i=1;i<=m;++i)cin>>a[i];
    a[m+1]=n+1;
    for(int i=1;i<=m+1;++i){
        ll wk=a[i]-1-a[i-1];
        if(a[i-1]-lstw==1&&wk+lstd>y){
            wk-=(y-lstd+1),ans+=1;
            ans+=wk/(y+2ll)*2ll,wk%=(y+2ll);
            if(wk>lstd){
                ans+=1,wk-=(lstd+1);
            }
        }
        if(wk>x){
            if(2ll*x<=y){
                ans+=wk/(x+1ll),wk=wk%(x+1ll);
                if(wk==0)lstw=a[i]-2;
                else lstw=a[i]-1;
            }else{
                ans+=wk/(y+2ll)*2ll,wk%=(y+2ll);
                if(wk==0)lstw=a[i]-2;
                else{
                    if(wk>x){
                        ans+=1,wk-=(x+1);
                        if(wk==0)lstw=a[i]-2;
                        else lstw=a[i]-1;
                    }else lstw=a[i]-1;
                }
            }
        }else lstw=a[i]-1;
        lstd=wk;
    }
    cout<<ans;
    return 0;
}