// #pragma GCC optimize("O3,Ofast,unroll-loops")
// #pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#include <bits/stdc++.h>
using namespace std;
#define int long long int
#define MP make_pair
#define pb push_back
#define REP(i,n) for(int i = 0; (i) < (n); (i)++)
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
void fastio() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
}
const double EPS = 0.00001;
const int INF = 1e18 + 5;
const int N = 3e5+5;
const int ALPH = 26;
const int LGN = 25;
constexpr int MOD = 1e9+7;
int n,m,q;
inline void solve() {
int A, B;
cin >> n >> A >> B;
__int128_t space = (__int128_t)A / __gcd(A, B + 1) * B;
space = min(space, (__int128_t)INF);
int sp = (int)space;
vector<array<int, 2> > inter;
REP(i, n) {
int l, r;
cin >> l >> r;
if(r - l + 1 >= sp) {
cout << sp << "\n";
return;
}
l %= sp; r %= sp;
if(l > r) {
inter.pb({0, r});
inter.pb({l, sp - 1});
}
else {
inter.pb({l, r});
}
}
int last = 0;
int ans = 0;
sort(all(inter));
for(auto c : inter) {
c[0] = max(last, c[0]);
if(c[0] > c[1]) continue;
ans += c[1] - c[0] + 1;
last = c[1] + 1;
}
cout << ans << "\n";
}
signed main() {
fastio();
int test = 1;
//cin>>test;
while(test--) {
solve();
}
}
