#include <bits/stdc++.h>
using i64 = long long;
constexpr i64 inf = 1e18 + 100;
int main(){
std::ios::sync_with_stdio(false);
std::cin.tie(nullptr);
i64 n, A, B;
std::cin >> n >> A >> B;
i64 gcd = std::__gcd(A, B + 1);
i64 cycle = A / gcd;
if (A / gcd > inf / B) {
cycle = inf;
} else {
cycle *= B;
}
std::vector<std::pair<i64, i64>> v;
for (int i = 0; i < n; i++) {
i64 l, r;
std::cin >> l >> r;
if (r - l + 1 >= cycle) {
std::cout << cycle << "\n";
return 0;
}
l %= cycle;
r %= cycle;
if (l <= r) {
v.emplace_back(l, r);
} else {
v.emplace_back(0, r);
v.emplace_back(l, cycle - 1);
}
}
sort(v.begin(), v.end());
std::vector<std::pair<i64, i64>> nw;
nw.push_back(v[0]);
for (int i = 1; i < int(v.size()); i++) {
if (nw[nw.size() - 1].second >= v[i].first) {
nw[nw.size() - 1].first = std::min(nw[nw.size() - 1].first, v[i].first);
nw[nw.size() - 1].second = std::max(nw[nw.size() - 1].second, v[i].second);
} else {
nw.emplace_back(v[i]);
}
}
i64 ans = 0;
for (auto [l, r] : nw) {
ans += r - l + 1;
}
std::cout << ans << '\n';
}
