#include <bits/stdc++.h>
#define FAST ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);cerr.tie(0)
#define mp make_pair
#define xx first
#define yy second
#define pb push_back
#define pf push_front
#define popb pop_back
#define popf pop_front
#define all(x) x.begin(),x.end()
#define ff(i,a,b) for (int i = a; i < b; i++)
#define fff(i,a,b) for (int i = a; i <= b; i++)
#define bff(i,a,b) for (int i = b-1; i >= a; i--)
#define bfff(i,a,b) for (int i = b; i >= a; i--)
using namespace std;
long double typedef ld;
unsigned int typedef ui;
long long int typedef li;
pair<int,int> typedef pii;
pair<li,li> typedef pli;
pair<ld,ld> typedef pld;
vector<vector<int>> typedef graph;
unsigned long long int typedef ull;
//const int mod = 998244353;
const int mod = 1000000007;
//Note to self: Check for overflow
map<li,vector<pli>> segs;
set<li> kords;
map<li,li> cisti;
int main()
{
FAST;
int n; cin>>n;
li A,B; cin>>A>>B;
li d=__gcd(A,B+1);
A/=d;
vector<pli> ulaz;
while (n--)
{
li l,r; cin>>l>>r;
if (A<LONG_LONG_MAX/B) l%=(A*B),r%=(A*B);
if (l>r) ulaz.pb({0,r}),ulaz.pb({l,A*B-1});
else ulaz.pb({l,r});
}
for (auto [l,r] : ulaz)
{
if (r/A == l/A) segs[l/A].pb({l%A,r%A}),kords.insert(l/A);
else
{
segs[l/A].pb({l%A,A-1});
segs[r/A].pb({0,r%A});
cisti[l/A+1]++;
cisti[r/A]--;
kords.insert(l/A);
kords.insert(l/A+1);
kords.insert(r/A);
}
}
li ans=0;
li kolkoclear=0;
li majmuncina=-1;
for (auto x : kords)
{
bool staromeso=false;
if (kolkoclear==0) staromeso=true;
kolkoclear+=cisti[x]; //cout<<x<<": "<<cisti[x]<<endl;
if (kolkoclear>0 && staromeso) majmuncina=x;
//cout<<"marmun "<<kolkoclear<<endl;
if (kolkoclear==0 && majmuncina!=-1) ans+=(x-majmuncina)*A,majmuncina=-1;
if (kolkoclear==0)
{
vector<pair<li,li>> lensi;
for (auto it : segs[x]) lensi.pb({it.xx,1}),lensi.pb({it.yy+1,-1});
sort(all(lensi));
li preth=-1;
li kolkocur=0;
for (auto y : lensi)
{
if (preth!=-1 && kolkocur) ans+=y.xx-preth;
preth=y.xx; kolkocur+=y.yy;
}
}
}
cout<<ans<<"\n";
}
//Note to self: Check for overflow
