#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll,ll> pii;
#define f first
#define s second
// number x and x + (a / gcd(a, b+1) * b) are equal
ll gcd(ll a, ll b){
if(b == 0) return a;
return gcd(b, a%b);
}
bool overflow(ll a, ll b){
ll v = a*b;
if(a == v/b) return true;
return false;
}
const ll inf = 1e18;
int main(){
ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
int n;
ll a, b;
cin >> n >> a >> b;
ll aux = a / (gcd(a, b+1));
bool ok = overflow(aux, b);
ll m = (ok ? aux * b : inf + 1);
vector<pii> v;
bool mx = 0;
for(int i=0; i<n; i++){
ll l, r;
cin >> l >> r;
if(r-l+1 > m) mx = 1;
l = l % m, r = r % m;
if(n == 1){
if(mx) cout << m << "\n";
else cout << r-l+1 << "\n";
return 0;
}
if(l <= r){
v.push_back({l, r});
v.push_back({r, inf + 5});
}
else{
v.push_back({l, m-1});
v.push_back({m-1, inf + 5});
v.push_back({0, r});
v.push_back({r, inf + 5});
}
}
if(mx){
cout << m << "\n";
return 0;
}
multiset<ll> s;
ll ans = 0;
sort(v.begin(), v.end());
for(pii x : v){
ll l = x.f, r = x.s;
//cout << l << " " << r << "\n";
if(r == inf + 5){ // out
s.erase(s.find(-l));
}
else{ // in
if(s.empty()) ans += r-l+1;
else{
ll mxx = -(*s.begin());
ans += max(0LL, r-mxx);
}
s.insert(-r);
}
}
cout << ans << "\n";
return 0;
}
