#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
typedef __int128_t int128; // Juda katta sonlar uchun
long long gcd(long long a, long long b) {
while (b) {
a %= b;
swap(a, b);
}
return a;
}
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int n;
long long A, B;
cin >> n >> A >> B;
// Davrni hisoblash: T = (A / gcd(A, B + 1)) * B
long long common = gcd(A, B + 1);
int128 T_val = (int128)A / common * B;
long long T;
const long long INF = 2e18; // Maksimal chegara
if (T_val >= INF) T = INF;
else T = (long long)T_val;
vector<pair<long long, long long>> segments;
for (int i = 0; i < n; i++) {
long long l, r;
cin >> l >> r;
if (r - l + 1 >= T) {
// Agar oraliq davrdan katta bo'lsa, hamma nuqtalar qoplanadi
cout << (long long)T << endl;
return 0;
}
l %= T;
r %= T;
if (l <= r) {
segments.push_back({l, r});
} else {
// Davrdan o'tib ketgan qismini ikkiga bo'lamiz
segments.push_back({l, T - 1});
segments.push_back({0, r});
}
}
// Segmentlarni birlashtirish (Interval Merging)
sort(segments.begin(), segments.end());
long long total_ans = 0;
if (!segments.empty()) {
long long curL = segments[0].first;
long long curR = segments[0].second;
for (size_t i = 1; i < segments.size(); i++) {
if (segments[i].first <= curR) {
curR = max(curR, segments[i].second);
} else {
total_ans += (curR - curL + 1);
curL = segments[i].first;
curR = segments[i].second;
}
}
total_ans += (curR - curL + 1);
}
cout << total_ans << endl;
return 0;
}
