#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define lll __int128_t
#define flt double
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
lll gcd(lll a, lll b) {
while (a != 0) {
b %= a;
swap(a, b);
}
return b;
}
int32_t main() {
if (1) {
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
}
int n;
ll A, B;
cin >> n >> A >> B;
lll t = (lll)(B) * (A / gcd(A, B + 1));
vector<pair<ll, int>> f;
f.reserve(n * 4);
for (int i = 0; i < n; i += 1) {
ll l, r;
cin >> l >> r;
r += 1;
if (r - l >= t) {
f.push_back(make_pair(0, 1));
f.push_back(make_pair(t, -1));
continue;
}
ll nl = l % t;
ll nr = r % t;
if (nl < nr) {
f.push_back(make_pair(nl, 1));
f.push_back(make_pair(nr, -1));
continue;
}
f.push_back(make_pair(nl, 1));
f.push_back(make_pair(t, -1));
f.push_back(make_pair(0, 1));
f.push_back(make_pair(nr, -1));
}
sort(all(f));
ll count = 0;
ll biba = 0;
for (int i = 0; i + 1 < (int)f.size(); i += 1) {
biba += f[i].second;
if (biba > 0) {
count += f[i + 1].first - f[i].first;
}
}
cout << count << "\n";
/*
vector<ll> usd(t, 0);
for (int i = 0; i < n; i += 1) {
ll l, r;
cin >> l >> r;
for (int j = l; j <= r; j += 1) {
usd[j % t] = 1;
}
}
ll count = 0;
for (int j = 0; j < t; j += 1) {
count += usd[j];
}
cout << count << "\n";
*/
return 0;
}
