#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define sz size()
#define ff first
#define ss second
#define pb push_back
#define pii pair <ll, ll>
#define dur exit(0)
#define dur1 return(0)
const int N = 2e5 + 5;
ll n, A, B;
int main () {
// freopen ("input.txt", "r", stdin);
ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
cin >> n >> A >> B;
__int128 rep = (__int128)A / (__int128)__gcd (A, B + 1) * (__int128)B;
vector <pii> v;
for (int i = 1; i <= n; ++i) {
int l, r;
cin >> l >> r;
if (r - l + 1 >= rep) {
v.pb ({0, rep - 1});
}
else if (l % rep <= r % rep) {
v.pb ({l % rep, r % rep});
}
else {
v.pb ({l % rep, rep - 1});
v.pb ({0, r % rep});
}
}
sort (v.begin(), v.end());
ll jogap = 0;
ll l = -1, r = -1;
for (pii i : v) {
if (~l) {
if (l <= i.ff and i.ff <= r) {
r = max (r, i.ss);
}
if (i.ff > r) {
jogap += r - l + 1;
l = i.ff;
r = i.ss;
}
}
else {
l = i.ff, r = i.ss;
}
}
jogap += r - l + 1;
cout << jogap;
}
/*
3 3 3
4 4
7 9
17 18
3 5 10
1 20
50 68
89 98
2 16 13
2 5
18 18
*/
