//#pragma comment(linker, "/stack:200000000")
//#pragma GCC optimize("Ofast")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define endl "\n"
#define all(c) (c).begin(),(c).end()
// when you ponder, divide and conquer
signed main() {
// freopen("input.txt", "r", stdin); freopen("output.txt", "w", stdout);
std::ios::sync_with_stdio(false);
cin.tie(0);
ll n, a, b;
cin >> n >> a >> b;
set<pair<ll, ll>> s;
for (int i = 0; i < n; i++) {
ll l, r;
cin >> l >> r;
for (int t = l; t <= r; t++)
s.emplace((t+t/b) % a, t%b);
}
cout << s.size() << endl;
}
/* --- PSolving ---
* Simplifying (getting rid of variables, conditions, code logic, etc.)
* Reframing
* Solving a subtask (subgoal, aux. problem, removing a condition or fixing a parameter, etc.)
* Inducing
* Divide and conquer
* Working backwards
* Visual intuition
* !! Reductions don't have to be specializations, they can be generalizations
*/
