#include<bits/stdc++.h>
using namespace std;
typedef long long int ll;
typedef long double ld;
#define FOR(i,l,r) for(ll i=l;i<r;i++)
#define REP(i,n) FOR(i,0,n)
#define RFOR(i,l,r) for(ll i=r-1;i>=l;i--)
#define RREP(i,n) RFOR(i,0,n)
#define ALL(x) x.begin(),x.end()
#define PA pair<ll,ll>
#define F first
#define S second
#define BS(A,x) binary_search(ALL(A),x)
#define LB(A,x) (ll)(lower_bound(ALL(A),x)-A.begin())
#define UB(A,x) (ll)(upper_bound(ALL(A),x)-A.begin())
#define COU(A,x) (UB(A,x)-LB(A,x))
#define sz(c) ((ll)(c).size())
template<typename T>using min_priority_queue=priority_queue<T,vector<T>,greater<T>>;
template<class T>bool chmax(T&a,T b){if(a<b){a=b;return 1;}return 0;}
template<class T>bool chmin(T&a,T b){if(b<a){a=b;return 1;}return 0;}
template<class T>void print(vector<T>A){REP(i,A.size()){if(i)cout<<" ";cout<<A[i];}cout<<endl;}
ld dist(ld x1,ld y1,ld x2,ld y2){return sqrtl((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));}
//const ll mod=1000000007;
//const ll mod=998244353;
int main(){
ll N,A,B;cin>>N>>A>>B;
vector<PA>S;
A/=__gcd(A,B+1);
ll X=2e18;
if(B<=2e18/A)X=A*B;
REP(i,N){
ll L,R;cin>>L>>R;
if(R-L>=X){cout<<X<<endl;return 0;}
L%=X;R%=X;
if(L>R){
S.emplace_back(PA(L,X));
S.emplace_back(PA(0,R+1));
}
else S.emplace_back(PA(L,R+1));
}
set<ll>Q;
for(auto[l,r]:S)Q.insert(l),Q.insert(r);
vector<ll>R;
for(auto q:Q)R.emplace_back(q);
ll M=sz(R);
vector<ll>D(M);
for(auto[l,r]:S)D[LB(R,l)]++,D[LB(R,r)]--;
REP(i,M)D[i+1]+=D[i];
ll ans=0;
REP(i,M-1)if(D[i])ans+=R[i+1]-R[i];
cout<<ans<<endl;
return 0;
}
