#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using ull = unsigned long long;
const bool typetest = 0;
const ll Inf = 2e18;
const int N = 1e5 + 5;
struct Trie
{
ll v;
Trie *child[2];
Trie()
{
v = -Inf;
child[0] = child[1] = NULL;
}
} beg;
ll k, m, d, a, b[N], dp[N];
int n;
ll t[N];
void Read()
{
cin >> k >> m >> d >> a >> n;
for (int i = 1; i <= n; ++i)
cin >> t[i] >> b[i];
t[0] = k;
t[n + 1] = m;
}
#define bit(i, x) (((x) >> (i)) & 1)
void Add(Trie *a, int x, ll v)
{
int id = 30;
while (1)
{
if (id == -1)
{
a->v = max(a->v, v);
return;
}
if (!(a->child[bit(id, x)]))
a->child[bit(id, x)] = new Trie;
a->v = max(a->v, v);
a = a->child[bit(id, x)];
--id;
}
}
ll Get_up(Trie *a, int x)
{
int id = 30;
ll ans(-Inf);
while (1)
{
if (id == -1)
{
ans = max(ans, a->v);
break;
}
if (bit(id, x))
{
if (a->child[1])
a = a->child[1];
else
break;
}
else
{
if (a->child[1])
ans = max(ans, a->child[1]->v);
if (a->child[0])
a = a->child[0];
else
break;
}
--id;
}
return ans;
}
ll Get_down(Trie *a, int x)
{
int id = 30;
ll ans(-Inf);
while (1)
{
if (id == -1)
{
ans = max(ans, a->v);
break;
}
if (!bit(id, x))
{
if (a->child[0])
a = a->child[0];
else
break;
}
else
{
if (a->child[0])
ans = max(ans, a->child[0]->v);
if (a->child[1])
a = a->child[1];
else
break;
}
--id;
}
return ans;
}
void Solve()
{
Add(&beg, t[0] % d, t[0] / d * a);
for (int i = 1; i <= n + 1; ++i)
{
dp[i] = Get_up(&beg, t[i] % d) - t[i] / d * a;
if (t[i] % d > 0)
dp[i] = max(dp[i], Get_down(&beg, t[i] % d - 1) - t[i] / d * a - a);
dp[i] += b[i];
Add(&beg, t[i] % d, dp[i] + t[i] / d * a);
}
cout << dp[n + 1];
}
int32_t main()
{
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int t(1);
if (typetest)
cin >> t;
for (int _ = 1; _ <= t; ++_)
{
Read();
Solve();
}
}
