#include <bits/stdc++.h>
using namespace std;
#define f first
#define s second
#define pb push_back
#define mp make_pair
#define all(v) v.begin(), v.end()
#define sz(v) (int)v.size()
#define MOO(i, a, b) for(int i=a; i<b; i++)
#define M00(i, a) for(int i=0; i<a; i++)
#define MOOd(i,a,b) for(int i = (b)-1; i >= a; i--)
#define M00d(i,a) for(int i = (a)-1; i>=0; i--)
#define FAST ios::sync_with_stdio(0); cin.tie(0);
#define finish(x) return cout << x << '\n', 0;
#define dbg(x) cerr << ">>> " << #x << " = " << x << "\n";
#define _ << " _ " <<
template<class T> bool ckmin(T& a, const T& b) {return b < a ? a = b, 1 : 0;}
template<class T> bool ckmax(T& a, const T& b) {return a < b ? a = b, 1 : 0;}
typedef unsigned long long ull;
typedef long long ll;
typedef long double ld;
typedef vector<int> vi;
typedef pair<int,int> pi;
typedef pair<ld,ld> pd;
typedef complex<ld> cd;
const int MAX_N = 1000010;
const ll inf = (ll)(2e18);
int n;
ll A, B;
ll gcd(ll a, ll b) {
if(a > b) swap(a,b);
if(a == 0) return b;
return gcd(b%a, a);
}
bool overflow(ull a, ull b) {
ll val = a*b;
if(val / b == a) return 0;
return val <= inf;
}
int main() { FAST
cin >> n >> A >> B;
ll period = A/gcd(A,B+1);
if(overflow(B, period)) {
period = inf;
} else {
period = B * period;
}
vector<pair<ll,ll>> intervals;
M00(i, n) {
ll l, r; cin >> l >> r;
if(r-l+1 >= period) {
finish(period);
}
l %= period;
r %= period;
if(l <= r) intervals.pb(mp(l, r));
else {
intervals.pb(mp(l, period-1));
intervals.pb(mp(0,r));
}
}
sort(all(intervals));
ll last = -1;
ll res = 0;
for(pair<ll,ll> interval: intervals) {
if(interval.f > last) {
res += interval.s - interval.f + 1;
} else {
if(interval.s > last) res += interval.s - last;
}
ckmax(last, interval.s);
}
finish(res);
}
