#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define ll long long
#define endl "\n"
using namespace std;
using namespace __gnu_pbds;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
template <typename T, typename key = less_equal<T>>
using ordered_set = tree<T, null_type, key, rb_tree_tag, tree_order_statistics_node_update>;
map<ll, vector<pair<ll, ll>>> mp;
vector<pair<ll, ll>> all;
ll a, b;
void add_range(ll l, ll r)
{
if (l / b == r / b)
{
mp[l / b % a].push_back(make_pair(l % b, r % b));
return;
}
if (l % b == 0 and r % b == b - 1)
{
all.push_back(make_pair(l / b, r / b));
return;
}
ll x = (l + b - 1) / b * b, y = r / b * b;
add_range(l, x - 1);
add_range(x, y - 1);
add_range(y, r);
}
void Merge(vector<pair<ll, ll>> &v)
{
sort(v.begin(), v.end());
vector<pair<ll, ll>> nv;
ll last = -1;
for (auto [l, r] : v)
if (max(l, last + 1) <= r)
{
nv.push_back(make_pair(max(l, last + 1), r));
last = r;
}
v = nv;
}
bool contains(ll x)
{
ll pos = upper_bound(all.begin(), all.end(), make_pair(x, (ll)2e18)) - all.begin();
if (pos == 0) return false;
pos--;
if (all[pos].second < x) return false;
return true;
}
void solve()
{
ll n;
cin >> n >> a >> b;
a /= gcd(a, b + 1);
while (n--)
{
ll l, r;
cin >> l >> r;
add_range(l, r);
}
Merge(all);
ll ans = 0;
for (auto [l, r] : all) ans += (r - l + 1) * b;
for (auto [x, v] : mp)
if (!contains(x))
{
Merge(v);
for (auto [l, r] : v) ans += r - l + 1;
}
cout << ans << endl;
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
ll t = 1;
// precomp();
// cin >> t;
for (ll cs = 1; cs <= t; cs++)
solve();
// cerr << "\nTime elapsed: " << clock() * 1000.0 / CLOCKS_PER_SEC << " ms\n";
}
