/* be name khoda */
#define long_enable
#include <iostream>
#include <algorithm>
#include <cstring>
#include <numeric>
#include <vector>
#include <fstream>
#include <set>
#include <map>
using namespace std;
#ifdef long_enable
typedef long long int ll;
#else
typedef int ll;
#endif
typedef pair<ll, ll> pii;
typedef pair<pii, ll> ppi;
typedef pair<ll, pii> pip;
typedef vector<ll> vi;
typedef vector<pii> vpii;
#define forifrom(i, s, n) for (ll i = s; i < n; ++i)
#define forirto(i, n, e) for (ll i = (n) - 1; i >= e; --i)
#define fori(i, n) forifrom (i, 0, n)
#define forir(i, n) forirto (i, n, 0)
#define F first
#define S second
#define pb push_back
#define eb emplace_back
#define all(x) (x).begin(), (x).end()
#define smin(a, b) a = min(a, (b))
#define smax(a, b) a = max(a, (b))
#define debug(x) cout << #x << " -> " << (x) << endl
#define debug2(x, y) cout << #x << ' ' << #y << " -> " << (x) << ' ' << (y) << endl
#define debug3(x, y, z) cout << #x << ' ' << #y << ' ' << #z << " -> " << (x) << ' ' << (y) << ' ' << (z) << endl
#define debug4(x, y, z, t) cout << #x << ' ' << #y << ' ' << #z << ' ' << #t << " -> " << (x) << ' ' << (y) << ' ' << (z) << ' ' << (t) << endl
#define debuga(x, n) cout << #x << " -> "; fori (i1_da, n) { cout << (x)[i1_da] << ' '; } cout << endl
#define debugaa(x, n, m) cout << #x << " ->\n"; fori (i1_daa, n) { fori (i2_daa, m) { cout << (x)[i1_daa][i2_daa] << ' '; } cout << '\n'; } cout << endl
const ll MOD = 1000000007;
const long long BIG = 1446803456761533460LL;
#define XL (x << 1)
#define XR (XL | 1)
#define MD ((l + r) >> 1)
#define Add(a, b) a = ((a) + (b)) % MOD
#define Mul(a, b) a = (1LL * (a) * (b)) % MOD
// -----------------------------------------------------------------------
const ll maxn = 1000010;
const ll maxa = 2000000000000000000;
ll n, A, B, g, m;
map<ll, ll> seg;
void add(ll l, ll r) {
seg[l]++;
seg[r]--;
if (l >= r) {
seg[0]++;
seg[m]--;
}
}
int main() {
ios_base::sync_with_stdio(false), cin.tie(0), cout.tie(0);
cin >> n >> A >> B;
g = gcd(A, B + 1);
m = A / g;
if (B > maxa / m + 1) m = maxa;
else m *= B;
fori (i, n) {
ll l, r; cin >> l >> r; ++r;
add(l % m, r % m);
}
ll ans = 0;
ll lst = 0, ps = 0;
for (auto [x, v] : seg) {
if (ps) ans += x - lst;
lst = x, ps += v;
}
cout << ans << '\n';
}
