#ifndef LOCAL
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#pragma GCC diagnostic ignored "-Wpedantic"
#endif
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
auto seed = chrono::high_resolution_clock::now().time_since_epoch().count();
mt19937 rnd(52);
template<typename T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template<typename T, typename V>
using table = gp_hash_table<T, V>;
using i128 = __int128;
using ll = long long;
using ld = long double;
using uint = unsigned int;
using ull = unsigned long long;
const ll INF = 2e18;
const int inf = 2e9;
const int maxn = 1e5;
const int MOD = 988244353;
const ld pi = acos(-1);
const int P = 5167;
const int L = 26;
const ld EPS = 1e-7;
template<typename T, typename V>
void fill(T &container, V value) {
for (auto &c: container)
c = value;
}
#define int ll
void solve() {
int n, a, b;
cin >> n >> a >> b;
i128 x = a / gcd(a, b + 1);
x *= b;
ll X = 0;
if (x > 5e18) X = 5e18;
else X = (ll) x;
vector<pair<int, int> > segs;
for (int i = 0; i < n; ++i) {
int l, r;
cin >> l >> r;
if (r - l + 1 < X) {
int k = r - l;
l %= X;
r = (l + k) % X;
} else {
int k = X - 1;
l %= X;
r = (l + k) % X;
}
if (l <= r) {
segs.push_back({l, r});
} else {
segs.push_back({l, X - 1});
segs.push_back({0, r});
}
}
sort(segs.begin(), segs.end());
int ans = 0;
int r = 0;
for (auto [L, R]: segs) {
if (r <= R) ans += R - max(r, L) + 1;
r = max(r, R + 1);
}
cout << ans;
}
signed main() {
#ifdef LOCAL
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
#endif
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
cout << fixed << setprecision(4);
int t = 1;
//cin >> t;
while (t--) solve();
//stress();
}
