/*
Unknown's C++ Template (v3.2)
*/
#include "bits/stdc++.h"
using namespace std;
#define int long long
using ll = long long;
using ld = long double;
using ii = pair<int, int>;
using vi = vector<int>;
using vii = vector<ii>;
using vvi = vector<vi>;
using vvii = vector<vii>;
template <class T> using maxpq = priority_queue<T>;
template <class T> using minpq = priority_queue<T, vector<T>, greater<T>>;
#define pb push_back
#define all(x) x.begin(), x.end()
#define sz(x) (int)x.size()
#define mid ((l+r)>>1)
#define fi first
#define se second
#ifdef LOCAL
#define debug(x) cout << #x << " = " << x << "\n";
#else
#define debug(x) ;
#endif
template <class A, class B>
ostream& operator << (ostream& out, pair<A, B> x)
{ out << "(" << x.first << ", " << x.second << ")"; return out; }
template <class T>
ostream& operator << (ostream& out, vector<T> x){
out << "[";
for (int i=0; i<sz(x); i++) { out << (i ? ", " : "") << x[i]; }
out << "]"; return out;
}
template <class T>
istream& operator >> (istream& in, vector<T> &x){
for (auto &i: x) in >> i;
return in;
}
const ld PI = acos(-1.0);
const int allmod[3] = {(int)1e9+7, 998244353, (int)1e9+9};
const int mod = allmod[0];
const int maxn = 2e5 + 64;
const ll inf = 1e18;
const ld eps = 1e-6;
const int multitest = 0;
int mult(int a, int b){
if ((a > 4e18 / b) || (b > 4e18 / a)) return 4e18;
return a * b;
}
void main_program(){
int n, A, B; cin >> n >> A >> B;
int g = __gcd(A, B + 1);
int m = A / g;
int md = mult(m, B);
vii crr;
for (int i = 0; i < n; i++){
int L, R; cin >> L >> R;
// L = a * md + b
// R = c * md + d
int a = L / md, b = L % md, c = R / md, d = R % md;
debug(a); debug(b); debug(c); debug(d);
if (b <= d){
if (a == c) crr.emplace_back(b, d);
else{
cout << md << "\n";
return;
}
}
else{
if (a + 1 == c){
crr.emplace_back(b, md - 1);
crr.emplace_back(0, d);
}
else{
cout << md << "\n";
return;
}
}
}
sort(all(crr)); debug(crr);
int lim = 0, res = 0;
for (auto [i, j]: crr){
lim = max(lim, i);
res += max(0LL, j - lim + 1);
lim = max(lim, j+1);
}
cout << res << "\n";
}
void pre_main(){
}
signed main(){
#ifdef LOCAL
auto stime = chrono::high_resolution_clock::now();
#endif
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#ifndef ONLINE_JUDGE
if (fopen(".inp", "r")){
freopen(".inp", "r", stdin);
freopen(".out", "w", stdout);
}
#endif
int t = 1; if (multitest) cin >> t;
pre_main();
while (t--) main_program();
#ifdef LOCAL
auto etime = chrono::high_resolution_clock::now();
auto duration = chrono::duration_cast<chrono::milliseconds>(etime-stime).count();
cout << "\n[" << duration << "ms]\n";
#endif
}
