#include <bits/stdc++.h>
#define SZ(v) ((int)(v).size())
using namespace std;
using ll = long long;
template<typename... Args>
void read(Args&... args)
{
((cin >> args), ...);
}
template<typename T>
void read(vector<T> &vec)
{
for (auto &v : vec) read(v);
}
void write() {}
template<typename H, typename... T>
void write(const H &h, const T&... t)
{
cout << h;
if (sizeof...(t)) {cout << ' '; write(t...);}
}
template<typename T>
void write(const vector<T> &vec)
{
if (SZ(vec) == 0) return;
write(vec[0]);
for (int i(1); i < SZ(vec); ++i)
{cout << ' '; write(vec[i]);}
}
template<typename... Args>
void writeln(Args... args)
{
write(args...); cout << '\n';
}
int main(void)
{
ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
int n;
ll A, B;
read(n, A, B);
ll mod = (A * B) / gcd(A, B+1);
vector<pair<ll, ll>> intervals;
for (int i(0); i < n; ++i)
{
ll l, r;
read(l, r);
l %= mod, r %= mod;
if (l > r)
{
intervals.emplace_back(l, mod-1);
intervals.emplace_back(0, r);
}
else
intervals.emplace_back(l, r);
}
sort(intervals.begin(), intervals.end());
ll lst(-1);
ll sol(0);
for (auto [l, r] : intervals)
{
sol += max(0LL, r - max(l, lst+1) + 1);
lst = max(lst, r);
}
writeln(sol);
}
