#include <bits/stdc++.h>
#include <iostream>
#include <vector>
#include <algorithm>
#include <numeric>
#include <cstdlib>
#include <cmath>
#include <queue>
#include <stack>
#include <deque>
#include <fstream>
#include <iterator>
#include <set>
#include <map>
#include <unordered_map>
#include <iomanip>
#include <cctype>
#include <string>
#include <cassert>
#include <set>
#include <bitset>
#include <unordered_set>
#include <numeric>
#define all(a) a.begin(), a.end()
#define fast ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
#define pb push_back
#define ppi pair<int,pair<int,int>>
#define int int64_t
using namespace std;
// /\_/\
// (= ._.)
// / > \>
// encouraging cat
const int INF = 10000000000000000;
//const int mod = 1000000007;
const int mod = 998244353;
const int MAXN = 1e5 + 5;
const int MAXP = 103;
//ifstream fin('xor.in');
//ofstream fout('xor.out');
int dp[MAXN][MAXP];
signed main()
{
int fin, period, dmg, n;
cin >> fin >> period >> dmg >> n;
vector<int> pos(n, 0);
for (int i = 0;i < n;i++)
{
cin >> pos[i];
}
pos.pb(fin);
n++;
for (int i = 0;i < n;i++)
{
for (int j = 0;j < period;j++)
{
dp[i][j] = INF;
}
}
dp[0][pos[0] % period] = ((pos[0] - 1) / period) * dmg + pos[0];
for (int i = 0;i < n - 1;i++)
{
for (int j = 0;j < period;j++)
{
int cr = dp[i][j];
int dist = pos[i + 1] - pos[i];
int stop = period - j; // time we wait at base if we want to stop
dp[i + 1][dist % period] = min(cr + ((dist - 1) / period) * dmg + (dist + stop), dp[i + 1][dist % period]);
int rem = (j + dist) % period;
dp[i + 1][rem] = min(dp[i + 1][rem], cr + ((j + dist - 1) / period) * dmg + dist);
}
}
int res = INF;
for (int j = 0;j < period;j++)
{
res = min(res, dp[n - 1][j]);
}
cout << res << '\n';
return 0;
}
