#include <bits/stdc++.h>
using namespace std;
#define ll long long
int main() {
ll n, a, b; cin >> n >> a >> b;
vector<pair<ll,ll>> turnedon(n);
__int128_t divisor = (__int128_t)gcd(a, b + 1);
__int128_t multiple = ((__int128_t)a * (__int128_t)(b + 1)) / divisor;
__int128_t num = multiple - (__int128_t)(multiple / (__int128_t)(b + 1));
for (int i=0;i<n;i++) {
cin >> turnedon[i].first >> turnedon[i].second;
}
ll limit;
if (num > 1000000000000000000) {
limit = 1000000000000000001;
} else {
limit = num;
}
vector<pair<ll,ll>> ansarr;
for (int i=0;i<n;i++) {
if (turnedon[i].second - turnedon[i].first + 1 >= limit) {
cout << limit;
return 0;
}
turnedon[i].first %= limit; turnedon[i].second %= limit;
if (turnedon[i].first > turnedon[i].second) {
ansarr.push_back(make_pair(turnedon[i].first, limit - 1));
ansarr.push_back(make_pair(0, turnedon[i].second));
} else {
ansarr.push_back(make_pair(turnedon[i].first, turnedon[i].second));
}
}
sort(ansarr.begin(), ansarr.end());
ll ans = 0, tracker = -1;
for (pair<ll,ll> j: ansarr) {
if (tracker < j.first) {
ans += j.second - j.first + 1;
tracker = j.second;
} else if (tracker < j.second) {
ans += j.second - tracker;
tracker = j.second;
}
}
cout << ans;
}
