#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int main() {
cin.tie(0)->sync_with_stdio(0);
int n;
ll A, B;
cin >> n >> A >> B;
vector<ll> l(n), r(n);
for (int i = 0; i < n; i++)
cin >> l[i] >> r[i];
ll reps = A / __gcd(A, B + 1);
map<ll, vector<pair<ll, bool>>> mlvl;
mlvl[B] = {};
map<ll, ll> mli;
for (int i = 0; i < n; i++) {
ll row1 = l[i] / B, row2 = r[i] / B;
if (row1 == row2) {
mlvl[l[i] % B].emplace_back(row1, 1);
mlvl[r[i] % B + 1].emplace_back(row1, 0);
} else {
mlvl[l[i] % B].emplace_back(row1, 1);
mlvl[B].emplace_back(row1, 0);
if (row1 + 1 < row2) {
ll lr = row1 + 1, rr = row2 - 1;
if (rr - lr + 1 >= reps) {
cout << reps * B << "\n";
return 0;
}
lr %= reps, rr %= reps;
if (lr <= rr) {
mli[lr]++;
mli[rr + 1]--;
} else {
mli[lr]++;
mli[reps]--;
mli[0]++;
mli[rr + 1]--;
}
}
mlvl[0].emplace_back(row2, 1);
mlvl[r[i] % B + 1].emplace_back(row2, 0);
}
}
vector<pair<ll, ll>> perm;
ll ct = 0;
for (auto a : mli) {
if (ct == 0 && a.second >= 0) {
perm.emplace_back(a.first, -1);
} else if (ct > 0 && ct + a.second == 0) {
perm.back().second = a.first;
}
ct += a.second;
}
map<ll, int> temp;
ll sumrn = 0;
for (auto a : perm)
sumrn += a.second - a.first;
ll cur = 0, ans = 0;
for (auto &[in, vpllb] : mlvl) {
ans += (in - cur) * sumrn;
for (auto [row, stat] : vpllb) {
row %= reps;
auto it = upper_bound(perm.begin(), perm.end(),
make_pair(row, LLONG_MAX));
if (it == perm.begin() || row >= (it - 1)->second) {
if (stat) {
temp[row]++;
if (temp[row] == 1)
sumrn++;
} else {
temp[row]--;
if (temp[row] == 0)
sumrn--;
}
}
}
cur = in;
}
cout << ans << "\n";
}
