#pragma GCC optimize("Ofast", "unroll-loops")
#include <bits/stdc++.h>
using namespace std;
#define int long long
#define double long double
using pii = pair<int, int>;
template<typename T>
using prior = priority_queue<T, vector<T>, greater<T>>;
template<typename T>
using Prior = priority_queue<T>;
#define X first
#define Y second
#define ALL(x) (x).begin(), (x).end()
#define eb emplace_back
#define pb push_back
#define fastIO() ios_base::sync_with_stdio(false), cin.tie(0)
void solve() {
int n, A, B;
cin >> n >> A >> B;
int cyc = log10(A) - log10(__gcd(A, B+1)) + log10(B) > 18.01 ? (int)1E18 + 100 : A / __gcd(A, B+1) * B;
map<int, int> pre;
while (n--) {
int L, R;
cin >> L >> R;
if (R - L + 1 >= cyc) ++pre[0], --pre[cyc];
else {
L %= cyc, R %= cyc;
if (L > R) ++pre[L], --pre[cyc], ++pre[0], --pre[R+1];
else ++pre[L], --pre[R+1];
}
}
int ans = 0, sum = 0, lst = 0;
for (auto [key, val] : pre) {
if (sum) ans += key - lst;
sum += val, lst = key;
}
cout << ans << "\n";
}
int32_t main() {
fastIO();
int t = 1; // cin >> t;
while (t--) solve();
return 0;
}
