//#pragma GCC target("avx,avx2,sse,sse2,sse3,ssse3,sse4,abm,popcnt,mmx")
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef double db;
typedef long double ldb;
typedef complex<double> cd;
constexpr ll INF64 = 1'000'000'000'000'000'000, INF32 = 2'000'000'000, MOD = 1'000'000'007;
constexpr db PI = acos(-1);
constexpr bool IS_FILE = false, IS_TEST_CASES = false;
random_device rd;
mt19937 rnd32(rd());
mt19937_64 rnd64(rd());
template<typename T>
bool assign_max(T& a, T b) {
if (b > a) {
a = b;
return true;
}
return false;
}
template<typename T>
bool assign_min(T& a, T b) {
if (b < a) {
a = b;
return true;
}
return false;
}
template<typename T>
T square(T a) {
return a * a;
}
template<>
struct std::hash<pair<ll, ll>> {
ll operator() (pair<ll, ll> p) const {
return ((__int128)p.first * MOD + p.second) % INF64;
}
};
ll gcd(ll a, ll b) {
return (min(a, b) == 0 ? max(a, b) : gcd(min(a, b), max(a, b) % min(a, b)));
}
void solve() {
ll n, a, b;
cin >> n >> a >> b;
ll x = gcd(a, b + 1);
ll mod = a * b / x;
map<ll, ll> add;
for (ll i = 0; i < n; i++) {
ll l, r;
cin >> l >> r;
r++;
if (r - l >= mod) {
cout << mod << '\n';
return;
}
l %= mod;
r %= mod;
if (l <= r) {
add[l]++;
add[r]--;
} else {
add[0]++;
add[mod]--;
add[l]++;
add[r]--;
}
}
ll now = 0;
ll ans = 0;
ll lst = 0;
for (auto[a, b] : add) {
if (now) {
ans += a - lst;
}
lst = a;
now += b;
}
cout << ans << '\n';
}
int main() {
if (IS_FILE) {
freopen("", "r", stdin);
freopen("", "w", stdout);
}
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
ll t = 1;
if (IS_TEST_CASES) {
cin >> t;
}
for (ll i = 0; i < t; i++) {
solve();
}
}
