#include <bits/stdc++.h>
using namespace std;
#define dbgv(v) cout<<#v<<" = "; f(i,0,v.size()) cout<<v[i]<<" "; cout<<endl
#define dbga(a,x,y) cout<<#a<<" = "; f(i,x,y) cout<<a[i]<<" "; cout<<endl
#define erorp(x) cout<<#x<<"={"<<(x.F)<<" , "<<x.S<<"}"<<endl
#define eror(x) cout<<#x<<'='<<(x)<<endl
#define f_(i,a,b) for(int i=a;i>=b;i--)
#define f(i,a,b) for(int i=a;i<b;i++)
#define nb(x) __builtin_popcount(x)
#define all(v) v.begin(),v.end()
#define bit(n,k) (((n)>>(k))&1)
#define Add(x,y) x=(x+y)%mod
#define maxm(a,b) a=max(a,b)
#define minm(a,b) a=min(a,b)
#define lst(x) x[x.size()-1]
#define sz(x) int(x.size())
#define mp make_pair
#define ll long long
#define pb push_back
#define S second
#define F first
#define int ll
const int N=1e6+99,inf=1e18+99;
int n,A,B,mod;
ll ans;
vector<pair<int,int> > v;
void find(){
__int128 a=A,b=B,INF=inf;
a=a/__gcd(a,b+1);
mod=min(INF,a*b);
//eror(mod);
}
main(){
ios::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);
cin>>n>>A>>B;
find();
f(i,0,n){
int l,r;
cin>>l>>r;
if(l/mod+1<r/mod){
cout<<mod;
exit(0);
}
if(l/mod==r/mod){
v.pb(mp(l%mod,r%mod));
}
else{
v.pb(mp(l%mod,mod-1));
v.pb(mp(0,r%mod));
}
}
sort(all(v));
int mx=-1;
f(i,0,v.size()){
//erorp(v[i]);
ans+=max(0ll,v[i].F-mx-1);
maxm(mx,v[i].S);
}
ans+=mod-mx-1;
cout<<mod-ans;
}
