#include <bits/stdc++.h>
#define F first
#define S second
#define pb push_back
#define ppb pop_back
#define ep insert
#define endl '\n'
#define elif else if
#define pow pwr
#define sqrt sqrtt
#define int long long
#define y1 YONE
typedef unsigned long long ull;
using namespace std;
const int N=1e6+5;
int n,l[N],r[N],a,b;
__int128 A,B,L[N],R[N];
int32_t main(){
ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
cin>>n>>a>>b;
a/=__gcd(a,b+1);
A=a,B=b;
A*=B;
for (int i=1;i<=n;i++){
cin>>l[i]>>r[i];
L[i]=l[i];
R[i]=r[i];
}
vector<pair<__int128,__int128>> v;
for (int i=1;i<=n;i++){
if (R[i]-L[i]+1>=A) v.pb({0,A-1});
else{
if (R[i]%A>=L[i]%A) v.pb({L[i]%A,R[i]%A});
else{
v.pb({L[i]%A,A-1});
v.pb({0,R[i]%A});
}
}
}
sort(v.begin(),v.end());
//for (auto u:v) cout<<u.F<<' '<<u.S<<endl;
pair<__int128,__int128> cur=v[0];
vector<pair<__int128,__int128>> f;
for (auto u:v){
__int128 ll=max(cur.F,u.F),rr=min(cur.S,u.S);
if (ll>rr){
f.pb(cur);
cur=u;
}
else{
ll=min(cur.F,u.F);
rr=max(cur.S,u.S);
cur={ll,rr};
}
}
f.pb(cur);
int ans=0;
for (auto u:f){
__int128 len=u.S-u.F+1;
ans+=(int)len;
}cout<<ans<<endl;
return 0;
}
