#include <bits/stdc++.h>
#define PB push_back
#define ST first
#define ND second
//mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
//#include <ext/pb_ds/assoc_container.hpp>
//#include <ext/pb_ds/tree_policy.hpp>
//using namespace __gnu_pbds;
//typedef tree<int, null_type, less_equal<int>, rb_tree_tag, tree_order_statistics_node_update> ordered_set;
using namespace std;
using ll = long long;
using pi = pair<int, int>;
using vi = vector<int>;
int n;
ll a, b;
vector<pair<ll,int>>p;
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cin >> n >> a >> b;
ll g = __gcd(a, b + 1);
a /= g;
ll mod = a * b;
for(int i = 1; i <= n; ++i) {
ll l, r;
cin >> l >> r;
if(r - l + 1 >= mod) {
p.PB({0,1});
p.PB({mod,-1});
} else {
if(l % (mod) <= r % (mod)) {
p.PB({l % (mod), 1});
p.PB({(r % (mod)) + 1, -1});
} else {
p.PB({(l % (mod)), 1});
p.PB({mod, -1});
p.PB({0, 1});
p.PB({r % (mod) + 1, -1});
}
}
}
sort(p.begin(), p.end());
ll ans = 0;
int cnt = 0;
ll pr = 0;
for(auto it : p) {
if(cnt > 0) ans += it.ST - pr;
cnt += it.ND;
pr = it.ST;
}
cout << ans;
}
