#include <bits/stdc++.h>
#define ll long long
#define X first
#define Y second
#define MP make_pair
using namespace std;
const int N = 1e5 + 12;
const ll INF = 1e18;
ll gcd(ll x, ll y){ return (y == 0 ? x: gcd(y, x % y));}
int n;
ll A, B;
multiset<ll> st;
vector< pair< pair<ll, ll>, ll > > g;
int main () {
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin >> n >> A >> B;
ll period = gcd(A, B + 1);
bool exc = 0;
if(((INF + A - 1) / A + B - 1) / B < period){
exc = 1;
}
else{
period *= A * B;
}
ll res = 0;
for(int i = 1;i <= n;i++){
ll l, r;
cin >> l >> r;
if(exc){
res += r - l + 1;
continue;
}
if(l + period - 1 <= r){
cout << period;
return 0;
}
else{
l %= period, r %= period;
if(l <= r){
g.push_back(MP(MP(l, -1), r));
g.push_back(MP(MP(r, 1), l));
}
else{
g.push_back(MP(MP(l, -1), period - 1));
g.push_back(MP(MP(period - 1, 1), l));
g.push_back(MP(MP(0, -1), r));
g.push_back(MP(MP(r, 1), 0));
}
}
}
if(exc)
return cout << res, 0;
sort(g.begin(), g.end());
for(pair< pair<ll, ll>, ll> v: g){
if(v.X.Y < 0){
res += v.Y - v.X.X + 1;
if(!st.empty()){
ll z = *st.begin();
z *= -1;
res -= min(v.Y, z) - v.X.X + 1;
}
st.insert(-v.Y);
}
else{
st.erase(st.find(-v.X.X));
}
}
cout << res;
}
