/*
Shu soragda biz m-dan x_i we y_i gaytalanyar
m-in tapylshynyn prove shu asakda link dushindiryar
https://codeforces.com/blog/entry/67129?#comment-887900
*/
#include <bits/stdc++.h>
using namespace std;
#define ff first
#define ss second
#define sz size()
#define pii pair <ll, ll>
const int N = 1e7 + 5;
#define ll long long
#define pb push_back
vector <pii> v;
ll n, a, b, l[N], r[N];
int main () {
// freopen ("input.txt", "r", stdin);
ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
cin >> n >> a >> b;
__int128 m = (__int128)a / __gcd (a, b + 1) * b; // m - period
for (int i = 1; i <= n; ++i) {
cin >> l[i] >> r[i];
}
for (int i = 1; i <= n; ++i) {
if (r[i] - l[i] + 1 >= m) {
v.pb ({0, m - 1});
continue;
}
if (l[i] % m > r[i] % m) {
v.pb ({l[i] % m, m - 1});
v.pb ({0, r[i] % m});
}
else {
v.pb ({l[i] % m, r[i] % m});
}
}
sort (v.begin(), v.end());
ll l1 = v[0].ff, r1 = v[0].ss, jogap = 0;
for (int i = 1; i < (int)v.sz; ++i) {
if (v[i].ff <= r1) r1 = max (r1, v[i].ss);
else if (v[i].ff > r1) {
jogap += r1 - l1 + 1;
l1 = v[i].ff;
r1 = v[i].ss;
}
}
jogap += r1 - l1 + 1;
cout << jogap;
}
