#include <bits/stdc++.h>
using namespace std;
#define lll __int128
#define ll lll
#define pll pair<ll, ll>
#define f first
#define s second
#define ALL(x) (x).begin(), (x).end()
#define SZ(x) (int)((x).size())
#define pb push_back
#ifdef BALBIT
#define bug(...) cerr<<"#"<<__LINE__<<" "<<#__VA_ARGS__<<": ", _do(__VA_ARGS__)
template<typename T> void _do(T && x ){ cerr<<x<<endl; }
template<typename T, typename ...S> void _do(T && x , S&&...y){ cerr<<x<<", "; _do(y...);}
#define IOS()
#else
#define IOS() ios::sync_with_stdio(0),cin.tie(0)
#define endl '\n'
#define bug(...)
#endif // BALBIT
ll n,A,B,gg;
ll non_prime_inv(ll a, ll b)
{
ll b0 = b, t, q;
ll x0 = 0, x1 = 1;
if (b == 1) return 1;
while (a > 1) {
q = a / b;
t = b, b = a % b, a = t;
t = x0, x0 = x1 - q * x0, x1 = t;
}
if (x1 < 0) x1 += b0;
return x1;
}
pair<ll, ll> pos(ll a, ll b) {
// get the group for this time
ll an = ((a - b ) % A + A)%A;
ll grp = an % gg;
an /= gg;
ll K = an * non_prime_inv((B+1)/gg, (A)/gg) %(A/gg);
return {grp, K * B + b};
}
pair<ll, ll> gt(ll t) {
return {(t+t/B)%A, t%B};
}
void RD(ll & x) {
long long int t; cin>>t;
x = t;
}
signed main(){
IOS();
bug(1,2,3);
RD(n); RD(A); RD(B);
gg = __gcd(A,B+1);
vector<pll> mp;
lll GS = A/gg*(lll)B;
ll start = 0;
for (int i = 0; i<n; ++i) {
ll L, R; RD(L); RD(R);
if (R-L+1 >= GS) {
cout<<(long long int )GS<<endl; return 0;
}
++R;
pll lp=pos((L+L/B)%A, L%B);
ll Lto = lp.s%GS;
mp.pb({Lto % GS,1});
pll rp = pos((R+R/B)%A, R%B);
ll Rto = rp.s%GS;
mp.pb({Rto % GS,-1});
assert(lp.f == rp.f);
// bug(lp.f, Lto, Rto);
if (Lto > Rto) {
++start;
}
}
sort(ALL(mp));
mp.pb({GS, 0});
ll re = 0;
ll prev = 0;
for (auto &p : mp) {
if (start > 0) re += p.f - prev;
prev = p.f;
start += p.s;
}
cout<<(long long int)re<<endl;
}
