#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
#include <debug.h>
#endif
#define st first
#define nd second
#define pb push_back
#define pf push_front
#define _pb pop_back
#define _pf pop_front
#define lb lower_bound
#define ub upper_bound
#define mtp make_tuple
#define all(x) (x).begin(), (x).end()
#define sz(x) (int)(x).size()
typedef long long ll; typedef unsigned long long ull;
typedef double db; typedef long double ldb;
typedef pair<int, int> pi; typedef pair<ll, ll> pll;
typedef vector<int> vi; typedef vector<ll> vll; typedef vector<pi> vpi; typedef vector<pll> vpll;
typedef string str;
template<typename T> T gcd(T a, T b) { return (b == 0? a : gcd(b, a % b)); }
template<typename T> T lcm(T a, T b) { return a / gcd(a, b) * b; }
#define FOR(i, l, r) for (int (i) = (l); (i) <= (r); ++(i))
#define FOS(i, r, l) for (int (i) = (r); (i) >= (l); --(i))
#define EACH(i, x) for (auto &(i) : (x))
#define WHILE while
#define file "TEST"
mt19937 rd(chrono::steady_clock::now().time_since_epoch().count());
ll rand(ll l, ll r) { return uniform_int_distribution<ll>(l, r)(rd); }
/*
Tran The Bao
CTL - Da Lat
Cay ngay cay dem nhung deo duoc cong nhan
*/
const int N = 1e6 + 1;
int n;
ll A, B, S = 0, L = 0;
pll a[N];
namespace subtask1 {
map<pll, bool> d;
void solve() {
int rs = 0;
FOR(i, 1, n) {
ll l = a[i].st, r = a[i].nd;
for (ll t = l; t <= r; ++t) {
ll x = (t + t / B) % A, y = t % B;
if (d.count({x, y})) continue;
d[{x, y}] = 1;
++rs;
}
}
cout << rs;
}
}
namespace subtask2 {
ll rs = 0;
void solve() {
ll l = a[1].st, r = a[1].nd;
ll C = A / gcd(A, B + 1);
ll pr = max(r - (r % B - l % B + B) % B - 1, l - 1);
rs += (r - pr) * min((r - l + 1) / B + 1, C);
rs += (min(B, r - l + 1) - r + pr) * min(r / B - l / B, C);
cout << rs;
}
}
namespace subtask3456 {
void solve() {
}
}
signed main() {
ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
// freopen(file".inp", "r", stdin);
// freopen(file".out", "w", stdout);
cin >> n >> A >> B;
FOR(i, 1, n) {
cin >> a[i].st >> a[i].nd;
S += a[i].nd - a[i].st + 1;
L = max(L, a[i].nd - a[i].st + 1);
}
if (S <= 1e6) {
subtask1::solve();
return 0;
}
if (n == 1) {
subtask2::solve();
return 0;
}
return 0;
}
/*
1 7 9
5 9
*/
