#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <algorithm>
#include <cmath>
#include <vector>
#include <set>
#include <map>
#include <unordered_set>
#include <unordered_map>
#include <queue>
#include <ctime>
#include <cassert>
#include <complex>
#include <string>
#include <cstring>
#include <chrono>
#include <random>
#include <queue>
#include <bitset>
#define pb push_back
#define int long long
#define str string
using namespace std;
const int M = 1e9 + 7;
signed main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
int n, a, b;
cin >> n >> a >> b;
vector<pair<int, int>> pr(n);
for (int i = 0; i < n; i++) cin >> pr[i].first >> pr[i].second;
int g = gcd(a, b + 1);
a /= g;
__int128_t num = a * b;
if (n == 1) {
int l = pr[0].first, r = pr[1].second;
if (r - l >= num - 1) {
cout << (int) num;
} else {
if (l == r) {
cout << 1;
} else {
l %= num;
r %= num;
if (l < r) {
cout << r - l + 1;
} else {
cout << r + (int) num - l;
}
}
}
return 0;
}
vector<pair<__int128_t, int>> ev;
for (auto p : pr) {
int l = p.first, r = p.second;
l %= num;
r %= num;
if (r < l) {
ev.pb({l, 1});
ev.pb({num, -1});
ev.pb({0, 1});
ev.pb({r + 1, -1});
} else {
ev.pb({l, 1});
ev.pb({r + 1, -1});
}
}
sort(ev.begin(), ev.end());
int bal = 0;
__int128_t last = 0;
int ans = 0;
for (auto p : ev) {
__int128_t x = p.first;
int type = p.second;
if (bal) {
ans += (x - last);
}
last = x;
bal += type;
}
cout << ans;
}
