#include<iostream>
#include<algorithm>
#include<vector>
#include<queue>
#include<set>
#include<unordered_set>
using namespace std;
typedef long long ll;
typedef pair<ll,ll> P;
#define rep(i,n) for(int i=0;i<n;i++)
#define chmin(a,b) a=min(a,b)
#define chmax(a,b) a=max(a,b)
#define all(x) x.begin(),x.end()
ll gcd(ll a,ll b){
return (b?gcd(b,a%b):a);
}
int main(){
ll n,A,B;
cin>>n>>A>>B;
ll M=A/gcd(A,B+1)*B; //cerr<<M<<endl;
vector<P> v;
rep(i,n){
ll l,r;
cin>>l>>r;
ll L=l/M,R=r/M;
if(L+2<=R){
v.push_back(make_pair(0,+1));
v.push_back(make_pair(M,-1));
}
else if(L+1==R){
v.push_back(make_pair(0,+1));
v.push_back(make_pair(r%M+1,-1));
v.push_back(make_pair(l%M,+1));
v.push_back(make_pair(M,-1));
}
else{
v.push_back(make_pair(l%M,+1));
v.push_back(make_pair(r%M+1,-1));
}
}
sort(all(v));
ll ans=0,rui=0,bef=0;
for(auto e:v){
ll t=e.first,di=e.second;
//cout<<"#"<<t<<" "<<di<<endl;
ans+=(rui>0)*(t-bef);
rui+=di;
bef=t;
}
cout<<ans<<endl;
}
