#include<bits/stdc++.h>
using namespace std;
#define int long long
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<ld, ld> pld;
#define x first
#define y second
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define mt make_tuple
#define len(a) (int)(a).size()
#define all(a) (a).begin(), (a).end()
#define rall(a) (a).rbegin(), (a).rend()
struct Event {
int x, type, p;
Event() {}
Event(int x, int type, int p) : x(x), type(type), p(p) {}
};
bool operator<(const Event& a, const Event& b) {
return mt(a.x, a.type) < mt(b.x, b.type);
}
vector<Event> evs;
vector<pii> good;
void add_ev(int l, int r, int p) {
evs.eb(l, 0, p);
evs.eb(r + 1, 1, p);
}
bool check(int x) {
int l = -1, r = len(good);
while (r - l > 1) {
int mid = (l + r) / 2;
if (good[mid].y >= x) r = mid; else l = mid;
}
if (r == len(good)) return 0;
return good[r].x <= x;
}
int32_t main() {
ios::sync_with_stdio(false);
cin.tie(0);
int n, a, b;
cin >> n >> a >> b;
int period = a / __gcd(a, b + 1);
for (int i = 0; i < n; i++) {
int l, r;
cin >> l >> r;
int block_l = l / b, block_r = r / b;
if (block_l == block_r) {
add_ev(l % b, r % b, block_l % period);
} else {
if (block_r - block_l != 1) {
int L = (block_l + 1) % period, R = (block_r - 1) % period;
if (L <= R) {
good.eb(L, R);
} else {
good.eb(0, R);
good.eb(L, period - 1);
}
}
add_ev(l % b, b - 1, block_l % period);
add_ev(0, r % b, block_r % period);
}
}
sort(all(evs));
set<int> anime;
for (auto el : good) {
for (int i = el.x; i <= el.y; i++) anime.insert(i);
}
map<int, int> cnt;
int have = 0, ans = len(anime) * b;
for (int i = 0; i + 1 < len(evs); i++) {
if (!anime.count(evs[i].p)) {
if (evs[i].type == 0) {
cnt[evs[i].p]++;
if (cnt[evs[i].p] == 1) have++;
} else {
cnt[evs[i].p]--;
if (cnt[evs[i].p] == 0) have--;
}
}
ans += have * (evs[i + 1].x - evs[i].x);
}
cout << ans;
return 0;
}
