#include <bits/stdc++.h>
#pragma GCC optimize ("O3")
#pragma GCC target ("sse4")
using namespace std;
#define int long long int
const int N = 1000 + 10;
const int md = 1e9 + 7;
const int INF = 1e9;
int32_t main(int32_t argc, char *argv[]) {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int T = 1;
// cin >> T;
while (T--) {
int n, A, B;
cin >> n >> A >> B;
int T = 1e18 + 10;
A /= __gcd(A, B + 1);
if (A <= (LLONG_MAX / B))
T = A * B;
vector<pair<int, int>> seg;
for (int i = 1; i <= n; i++) {
int l, r;
cin >> l >> r;
if ((r - l + 1) >= T) {
cout << T << '\n';
return 0;
}
l %= T, r %= T;
if (l <= r) {
seg.push_back({l, r});
} else {
seg.push_back({l, T - 1});
seg.push_back({0, r});
}
}
sort(seg.begin(), seg.end());
int l = -1, r = -2;
int ans = 0;
for (int i = 0; i < (int) seg.size(); i++) {
auto [a, b] = seg[i];
if (r < a) {
ans += (r - l) + 1;
l = a, r = b;
} else {
r = max(r, b);
}
}
ans += (r - l) + 1;
cout << ans << '\n';
}
return 0;
}
