/**
* Prof.Nicola
**/
#include <bits/stdc++.h>
using namespace std;
#define endl "\n"
#define mp make_pair
#define F first
#define S second
#define REP(i,l,r) for(long long i=(l);i<(r);i++)
#define PER(i,l,r) for(long long i=(r)-1;i>=(l);i--)
#define bitl __builtin_clz
#define bitr __builtin_ctz
#define bits __builtin_popcount
const long dx[4]={1,0,-1,0},dz[4]={0,1,0,-1};
const long double pi=3.14159265359;
const long long mod=1e9+7;
long long p(long long x){while(x&(x-1)){x=x&(x-1);}return x;}
long long squared(long long x){return (x*x)%mod;}
long long power(long long x,long long p){if(p==0){return 1;}if(p%2==1){return (power(x,p-1)*x)%mod;}return squared(power(x,p/2));}
long long inv(long long x){return power(x,mod-2);}
long long log(long long x,long long z){if(x<z){return 0;}return 1+log(x/z,z);}
template<class T>void re(T&x){cin>>x;}
template<class T1,class T2> void re(pair<T1,T2>&x){re(x.first);re(x.second);}
template<class T>void re(vector<T>&x){for(long i=0;i<x.size();i++){re(x[i]);}}
template<class T>void re(deque<T>&x){for(long i=0;i<x.size();i++){re(x[i]);}}
template<class T>void out(T x){cout<<x<<" ";}
template<class T1,class T2>void out(pair<T1,T2>x){out(x.first);out(x.second);cout<<endl;}
template<class T>void out(vector<T>x,long l=0,long r=0){if(!r){r=x.size();}for(long i=l;i<r;i++){out(x[i]);}cout<<endl;}
template<class T>void out(deque<T>x,long l=0,long r=0){if(!r){r=x.size();}for(long i=l;i<r;i++){out(x[i]);}cout<<endl;}
template<class T>void out(set<T>x){while(!x.empty()){out(*x.begin());x.erase(*x.begin());}cout<<endl;}
template<class T1,class T2>void out(map<T1,T2>x){while(!x.empty()){out(*x.begin());x.erase(x.begin()->first);}cout<<endl;}
template<class T>void out(queue<T>x){while(!x.empty()){out(x.front());x.pop();}cout<<endl;}
template<class T>void out(priority_queue<T>x){while(!x.empty()){out(x.top());x.pop();}cout<<endl;}
template<class T>void out(stack<T>x){while(!x.empty()){out(x.top());x.pop();}cout<<endl;}
template<class T>T cross(complex<T>x,complex<T>z){return (conj(x)*z).imag();}
template<class T>T dot(complex<T>x,complex<T>z){return (conj(x)*z).real();}
set<long long>::iterator T;
long long vLE(long long x,vector<long long>&VT,long l=0,long r=-1){if(r==-1){r=VT.size()-1;}if(VT[l]>x){return -1;}long long z=p(r-l);while(z){if(l+z<=r&&VT[l+z]<=x){l+=z;}z/=2;}return l;}
long long vL(long long x,vector<long long>&VT,long l=0,long r=-1){if(r==-1){r=VT.size()-1;}if(VT[l]>=x){return -1;}long long z=p(r-l);while(z){if(l+z<=r&&VT[l+z]<x){l+=z;}z/=2;}return l;}
long long vGE(long long x,vector<long long>&VT,long l=0,long r=-1){if(r==-1){r=VT.size()-1;}if(VT[l]>=x){return l;}l=vL(x,VT,l,r);if(l==r){return -1;}return l+1;}
long long vG(long long x,vector<long long>&VT,long l=0,long r=-1){if(r==-1){r=VT.size()-1;}if(VT[l]>x){return l;}l=vLE(x,VT,l,r);if(l==r){return -1;}return l+1;}
long long sLE(long long x,set<long long>&ST){if(ST.count(x)){return x;}if(*ST.begin()>x){return -1;}ST.insert(x);T=ST.find(x);T--;ST.erase(x);return *T;}
long long sL(long long x,set<long long>&ST){if(*ST.begin()>=x){return -1;}if(ST.count(x)){T=ST.find(x);T--;return *T;}ST.insert(x);T=ST.find(x);T--;ST.erase(x);return *T;}
long long sGE(long long x,set<long long>&ST){if(ST.count(x)){return x;}if(*ST.rbegin()<x){return -1;}ST.insert(x);T=ST.find(x);T++;ST.erase(x);return *T;}
long long sG(long long x,set<long long>&ST){if(*ST.rbegin()<=x){return -1;}if(ST.count(x)){T=ST.find(x);T++;return *T;}ST.insert(x);T=ST.find(x);T++;ST.erase(x);return *T;}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
long long n,A,B,s,ans=0,l,r,mx;
cin>>n>>A>>B;
vector<pair<long long,long long> >v(n),srt;
re(v);
REP(i,0,n){
ans+=v[i].S-v[i].F+1;
}
if(log(A)+log(B)-log(__gcd(A,B+1))>log(2e18)){
cout<<ans<<endl;
return 0;
}
s=B*(A/__gcd(A,B+1));
REP(i,0,n){
if(v[i].S-v[i].F+1>=s){
cout<<s<<endl;
return 0;
}
l=v[i].F%s;
r=v[i].S%s;
if(l<=r){
srt.push_back(mp(l,r));
continue;
}
srt.push_back(mp(0,r));
srt.push_back(mp(l,s-1));
}
sort(srt.begin(),srt.end());
ans=srt[0].S-srt[0].F+1;
mx=srt[0].S;
REP(j,1,srt.size()){
mx=max(mx,srt[j].F-1);
ans+=max(0ll,srt[j].S-mx);
mx=max(mx,srt[j].S);
}
cout<<ans<<endl;
return 0;
}
