#include <bits/stdc++.h>
#define lp(i,a,b) for(int i = a; i < b; i++)
#define pb push_back
#define sz(x) (int)(x.size())
#define all(x) x.begin(),x.end()
#define debug printf
#define tiii tuple<int,int,int>
#define mkt make_tuple
#define pii pair<int,int>
#define mk make_pair
#define ll long long
#define ff first
#define ss second
using namespace std ;
int N ;
ll A , B , G , ans ;
vector< pair<ll,ll> > vectorInteiros , vectorParciais , intervalosInteiros ;
map< ll , vector< pair<ll,ll> > > miniLineSweep ;
bool pegueiInteiro(ll block)
{
auto it = upper_bound( all(intervalosInteiros) , mk(block,G+5) ) ;
if( it == intervalosInteiros.begin() ) return false ;
it-- ;
return (it->ff <= block && it->ss >= block) ;
}
int main()
{
scanf("%d%lld%lld", &N , &A, &B ) ;
G = __gcd(A,B+1);
G = A/G ;
const ll period = ( LLONG_MAX / B < G ) ? LLONG_MAX : B*G ;
for(int i = 1 ; i <= N ; i++ )
{
ll L , R ;
scanf("%lld %lld", &L , &R ) ;
if(R - L + 1LL >= period )
{
printf("%lld\n" , period ) ;
return 0 ;
}
ll actualL = ( (L+B)/B ) * B ;
ll actualR = ( (R-B)/B ) * B + B-1 ;
if(actualL - 1 >= L)
vectorParciais.pb( mk(L, min(actualL-1, R) ) ) ;
if(actualR+1 <= R)
vectorParciais.pb( mk(max(L,actualR+1), R ) ) ;
if( actualL > actualR ) continue ;
actualL /= B ;
actualR /= B ;
actualL %= G ;
actualR %= G ;
if(actualL > actualR )
{
vectorInteiros.pb( mk(actualL, G-1) ) ;
actualL = 0 ;
}
vectorInteiros.pb( mk(actualL, actualR) ) ;
}
if( sz(vectorInteiros) > 0 )
{
sort(all(vectorInteiros)) ;
ll mn = vectorInteiros[0].ff ;
ll mx = vectorInteiros[0].ss ;
vectorInteiros.pb( mk(G+5, G+5) ) ;
for(int i = 1 ; i < sz(vectorInteiros) ; i++ )
{
if( vectorInteiros[i].ff > mx )
{
intervalosInteiros.pb( mk(mn,mx) ) ;
ans += (mx - mn + 1LL ) * B ;
mn = vectorInteiros[i].ff ;
mx = vectorInteiros[i].ss ;
}
else if( vectorInteiros[i].ss > mx ) mx = vectorInteiros[i].ss ;
}
}
for(auto e : vectorParciais )
{
ll L = e.ff ;
ll R = e.ss ;
ll block = L/B ;
block %= G ;
L %= B ;
R %= B ;
miniLineSweep[ block ].pb( mk(L,R) ) ;
}
for(auto block : miniLineSweep )
{
if( pegueiInteiro(block.ff) ) continue ;
// debug("Estou vendo o modulo %d, e tenho nele:\n" , block.ff ) ;
vector< pair<ll,ll> > &sweep = block.ss ;
sort(all(sweep)) ;
// for(auto e :sweep ) debug("%lld %lld\n" ,e.ff, e.ss ) ;
// debug("\n") ;
ll mn = sweep[0].ff ;
ll mx = sweep[0].ss ;
sweep.pb( mk(B+5, B+5) ) ;
for(int i = 1 ;i < sz(sweep) ; i++ )
{
if(sweep[i].ff > mx )
{
ans += mx - mn + 1LL ;
mn = sweep[i].ff ;
mx = sweep[i].ss ;
}
else if( mx < sweep[i].ss ) mx = sweep[i].ss ;
}
}
printf("%lld\n" , ans ) ;
}
