#include <bits/stdc++.h>
using namespace std;
#define int long long
signed main(){
ios::sync_with_stdio(0);
cin.tie(0);
int b,p,d,n;
cin >> b >> p >> d >> n;
int dp[p];
iota(dp,dp+p,0);
int las = 0;
while(n--){
int a;
cin >> a;
///merge las-a range into dp
int len = a-las-1;
int base = (len/p)*d;
int tillpos = p-len%p;
for(int i = 0;i<p;i++){
dp[i]+=base;
if(i>=tillpos){
dp[i]+=d;
}
}
for(int i = 1;i<2*p;i++){
dp[i%p]=min(dp[i%p],dp[(i-1)%p]+1);
}
//shift
int temp[p];
int delta = (len+1)%p;
for(int i = 0;i<p;i++){
temp[(i+delta)%p]=dp[i];
}
for(int i = 0;i<p;i++){
dp[i]=temp[i];
}
las=a;
}
int a=b;
///merge las-a range into dp
int len = a-las-1;
int base = (len/p)*d;
int tillpos = p-len%p;
for(int i = 0;i<p;i++){
dp[i]+=base;
if(i>=tillpos){
dp[i]+=d;
}
}
for(int i = 1;i<2*p;i++){
dp[i%p]=min(dp[i%p],dp[(i-1)%p]+1);
}
//shift
int temp[p];
int delta = (len+1)%p;
for(int i = 0;i<p;i++){
temp[(i+delta)%p]=dp[i];
}
for(int i = 0;i<p;i++){
dp[i]=temp[i];
}
las=a;
int ans = *min_element(dp,dp+p);
ans+=b;
cout << ans;
return 0;
}
