#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize("O3")
typedef long long ll;
void setIo(){
ios::sync_with_stdio(false);
cin.tie(0);
}
#define all(c) (c).begin(), (c).end()
#define sz(c) (int)(c).size()
#define vt vector
#define pb push_back
#define F first
#define S second
#define pii pair<int,int>
#define mp make_pair
struct pair_hash {
template <class T1, class T2>
size_t operator()(const pair<T1, T2>& p) const {
return hash<T1>()(p.first) ^ (hash<T2>()(p.second) << 1);
}
};
void solve() {
int n; cin>>n;
ll A,B; cin>>A>>B;
unordered_set<pair<ll,ll>, pair_hash> s;
for (int i=0;i<n;i++){
ll l,r; cin>>l>>r;
for (int t=l;t<=r;t++){
s.insert(mp((t + t/B)%A, t % B));
}
}
cout << s.size() << endl;
}
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
solve();
return 0;
}
