#include <bits/stdc++.h>
 
#define ll long long
#define lb lower_bound
#define pii pair<int,int>
#define pll pair<ll,ll>
#define F first
#define S second
#define ld long double
#define pb push_back
#define all(v) v.begin(),v.end()
#define in insert
#define sz(s) (int)s.size()
#define ppb pop_back
#define mem(a,i) memset(a,i,sizeof(a))
#define int ll

using namespace std;
 
const int MAX=1e5+10;
const int inf=2e18;
const int mod=1e9+7;

const int dx[4]={1,0,-1,0};
const int dy[4]={0,1,0,-1};

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

int b,p,d,n;
int dp[MAX][110],a[MAX];

void solve(){
    cin>>b>>p>>d>>n;
    for(int i=1;i<=n;i++)cin>>a[i];
    a[0]=0;
    for(int i=0;i<=n;i++)for(int j=0;j<p;j++)dp[i][j]=inf;
    dp[0][0]=0;
    for(int i=0;i<=n;i++){
        for(int j=1;j<p;j++)dp[i][0]=min(dp[i][0],dp[i][j]+(p-j));
        for(int j=0;j<p;j++){
            int nxt=(j+(a[i+1]-a[i]))%p;
            int cnt=(a[i+1]-a[i]-1)/p;
            dp[i+1][nxt]=min(dp[i+1][nxt],dp[i][j]+cnt*d);
        }
    }
    int ans=inf;
    for(int i=0;i<=n;i++){
        int dist=b-a[i];
        ans=min(ans,dp[i][0]+((dist-1)/p)*d);
    }
    cout<<ans+b<<"\n";
}

signed main(){
    // freopen("escape.in","r",stdin);
    // freopen("escape.out","w",stdout);
    ios_base::sync_with_stdio(0);
    // cin.tie(0);
    // cout.tie(0);
    int t=1;
    // cin>>t;
    while(t--)solve();
}