/**
* @title Template
*/
#include <iostream>
#include <algorithm>
#include <utility>
#include <numeric>
#include <vector>
#include <array>
#include <map>
template <class T, class U>
inline bool chmin(T &lhs, const U &rhs) {
if (lhs > rhs) { lhs = rhs; return true; }
return false;
}
template <class T, class U>
inline bool chmax(T &lhs, const U &rhs) {
if (lhs < rhs) { lhs = rhs; return true; }
return false;
}
struct range {
using itr = int64_t;
struct iterator {
itr i;
constexpr iterator(itr i_) noexcept : i(i_) { }
constexpr void operator ++ () noexcept { ++i; }
constexpr itr operator * () const noexcept { return i; }
constexpr bool operator != (iterator x) const noexcept { return i != x.i; }
};
const iterator l, r;
constexpr range(itr l_, itr r_) noexcept : l(l_), r(std::max(l_, r_)) { }
constexpr iterator begin() const noexcept { return l; }
constexpr iterator end() const noexcept { return r; }
};
struct revrange {
using itr = int64_t;
struct iterator {
itr i;
constexpr iterator(itr i_) noexcept : i(i_) { }
constexpr void operator ++ () noexcept { --i; }
constexpr itr operator * () const noexcept { return i; }
constexpr bool operator != (iterator x) const noexcept { return i != x.i; }
};
const iterator l, r;
constexpr revrange(itr l_, itr r_) noexcept : l(l_ - 1), r(std::max(l_, r_) - 1) { }
constexpr iterator begin() const noexcept { return r; }
constexpr iterator end() const noexcept { return l; }
};
using i32 = int32_t;
using i64 = int64_t;
using u32 = uint32_t;
using u64 = uint64_t;
constexpr i32 inf32 = (i32(1) << 30) - 1;
constexpr i64 inf64 = (i64(1) << 62) - 1;
std::vector<std::pair<i64, i64>> resolve_overlapping(std::vector<std::pair<i64, i64>> vec) {
std::sort(vec.begin(), vec.end());
i64 L = -1, R = -1;
std::vector<std::pair<i64, i64>> res;
for (auto [l, r]: vec) {
if (R < l) {
if (L != -1 && R != -1) {
res.emplace_back(L, R);
}
L = l;
R = r;
}
else {
chmax(R, r);
}
}
if (L != -1 && R != -1) {
res.emplace_back(L, R);
}
return res;
}
int main() {
std::ios::sync_with_stdio(false);
std::cin.tie(nullptr);
size_t N;
i64 A, B;
std::cin >> N >> A >> B;
i64 C = (B % A) + 1;
i64 D = A / std::gcd(A, C);
std::vector<std::pair<i64, i64>> intervals;
intervals.reserve(N);
__int128_t loop = __int128_t(B) * __int128_t(D);
while (N--) {
i64 l, r;
std::cin >> l >> r;
i64 sl = l / loop;
i64 sr = r / loop;
switch (sr - sl) {
case 0:
intervals.emplace_back(l % loop, r % loop);
break;
case 1:
intervals.emplace_back(l % loop, loop - 1);
intervals.emplace_back(0, r % loop);
break;
default:
std::cout << (i64) loop << '\n';
return 0;
break;
}
}
intervals = resolve_overlapping(intervals);
std::vector<std::pair<i64, i64>> covered;
std::map<i64, std::vector<std::pair<i64, i64>>> fragments;
for (auto [l, r]: intervals) {
i64 sl = l / B;
i64 sr = r / B;
switch (sr - sl) {
case 0:
fragments[sl].emplace_back(l % B, r % B);
break;
case 1:
fragments[sl].emplace_back(l % B, B - 1);
fragments[sr].emplace_back(0, r % B);
break;
default:
covered.emplace_back(sl + 1, sr - 1);
fragments[sl].emplace_back(l % B, B - 1);
fragments[sr].emplace_back(0, r % B);
break;
}
}
covered = resolve_overlapping(covered);
i64 ans = 0, cover = 0;
for (auto [k, vec]: fragments) {
auto itr = std::upper_bound(covered.begin(), covered.end(), std::make_pair(k, i64(-1)));
if (itr != covered.begin()) {
itr = std::prev(itr);
if (itr -> second >= k) {
--cover;
continue;
}
}
vec = resolve_overlapping(vec);
for (auto [l, r]: vec) {
ans += r - l + 1;
}
}
for (auto [l, r]: covered) {
cover += r - l + 1;
}
std::cout << ans + B * cover << '\n';
return 0;
}
