#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii ;
typedef pair<ll, ll> pll ;
typedef vector<pii> vii ;
typedef vector<int> veci ;
typedef vector<pll> vll ;
typedef vector<ll> vecll;
typedef __uint128_t UL;
// find_by_order order_of_key
//#pragma GCC optimize("O3,unroll-loops")
//#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update>
#define F first
#define S second
#define pb push_back
#define endl '\n'
#define Mp make_pair
#define all(x) x.begin(), x.end()
#define debug(x) cerr << #x << " = " << x << endl
#define set_dec(x) cout << fixed << setprecision(x);
#define fast_io ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define file_io freopen("in.txt" , "r" , stdin) ; freopen("out.txt" , "w" , stdout);
#define lb lower_bound
#define ub upper_bound
#define for1(n) for(int i=1;i<=n;i++)
#define for0(n) for(int i=0;i<n;i++)
#define forn(n) for(int i=n;i>0;i--)
#define pq priority_queue <pii, vector<pii>, greater<pii>>
ll inf=1e18+100;
const int N=(1e6+10)*120;
int n,m,k,q,nn;
ll c,a,b;
vector<ll> seg;
vector<pii>nxt;
void upd(ll lx,ll rx,ll l=0,ll r=c,ll v=1){
if(seg[v]==r-l)return;
if(lx<=l && r<=rx){
seg[v]=r-l;
return;
}
ll mid=(l+r)>>1;
if(lx<mid){
if(nxt[v].F==0){
nxt[v].F=seg.size();
seg.pb(0);
nxt.pb({0,0});
}
upd(lx,rx,l,mid,nxt[v].F);
}
if(rx>mid){
if(nxt[v].S==0){
nxt[v].S=seg.size();
seg.pb(0);
nxt.pb({0,0});
}
upd(lx,rx,mid,r,nxt[v].S);
}
seg[v]=seg[nxt[v].F]+seg[nxt[v].S];
}
int main(){
fast_io
seg.pb(0);seg.pb(0);
nxt.pb({0,0});nxt.pb({0,0});
nn=1;
cin>>n>>a>>b;
UL tmp=a/__gcd(a,b+1)*b;
if(tmp>inf)c=inf;
else c=tmp;
for1(n){
ll l,r;cin>>l>>r;
if(r-l>=c)
return cout<<c<<endl,0;
l%=c;r%=c;
if(l<=r)
upd(l,r+1);
else{
upd(0,r+1);
upd(l,c);
}
}
cout<<seg[1]<<endl;
}
