// Problem: A - Strange Device
// Contest: Virtual Judge - 2024-02-27 APIO Simulation
// URL: https://vjudge.net/contest/612540#problem/A
// Memory Limit: 512 MB
// Time Limit: 5000 ms
//
// Powered by CP Editor (https://cpeditor.org)
#include <bits/stdc++.h>
using namespace std;
#define rep(i, a, b) for(int i = a; i < (b); ++i)
#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()
#define print(A,t) cerr << #A << ": "; copy(all(A),ostream_iterator<t>(cerr," " )); cerr << endl
#define prArr(A,n,t) cerr << #A << ": "; copy(A,A + n,ostream_iterator<t>(cerr," " )); cerr << endl
#define what_is(x) cerr << #x << " is " << x << endl
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef vector<int> vi;
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL); cout.tie(NULL);
int n; ll A, B; cin >> n >> A >> B;
set<pair<ll, ll>> ans;
for (int i = 1; i <= n; i++) {
ll L, R;
cin >> L >> R;
for (ll j = L; j <= R; j++) {
ll x = (j + j / B) % A;
ll y = j % B;
ans.insert({x, y});
}
}
cout << sz(ans) << endl;
return 0;
}
