#include <bits/stdc++.h>
/*
#pragma GCC optimize("O3")
#pragma GCC optimize("Ofast")
#pragma GCC target ("avx2")
*/
using namespace std;
/*
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
template<class T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
*/
#define F first
#define S second
#define pb push_back
#define FIO freopen("input.txt", "r", stdin);freopen("output.txt", "w", stdout)
#define md(a) ((a%mod+mod)%mod)
#define all(a) a.begin(), a.end()
#define MP make_pair
#define lc id<<1
#define rc lc|1
#define mid (l+r)/2
#define kill(a) cout << a << "\n", exit(0)
typedef pair<int,int> pii;
typedef pair<long long ,long long> pll;
typedef long long ll;
typedef long double ld;
typedef vector<vector<ll>> matrix;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
ll const maxn=1e5+10, mod=1e9+7, INF=1e18, LOG=9, sq=65;
ll poww(ll a, ll b, ll mod) {
if (b == 0) return 1;
return 1 * poww(1 * a * a % mod, b / 2, mod) * ((b % 2 == 1) ? a : 1) % mod;
}
ll n, a, b;
int main()
{
ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
cin>>n>>a>>b;
ll x=(a/__gcd(a, b+1));
ll y;
ll l1=120, l2=120;
ll q=1;
for(ll i=1;i<=20;i++)
{
q*=10;
if(q>x) {
l1=i-1;
break;
}
}
q=1;
for(ll i=1;i<=20;i++)
{
q*=10;
if(q>b) {
l2=i-1;
break;
}
}
if((l1+l2)<18) y=x*b;
else y=1000000000000000000+10;
ll ans=0;
vector<pll> v;
bool g=0;
//cout<<y<<"\n";
for(ll i=1;i<=n;i++)
{
ll l,r;
cin>>l>>r;
if(r-l+1>=y) g=1;
else
{
ll a=l%y;
if(a==0) a=y;
ll b=r%y;
if(b==0) b=y;
if(a<=b)
{
v.pb({a, b});
}
else
{
v.pb({a, y});
v.pb({1, b});
}
}
}
if(g) kill(y);
if(y!=-1)
{
sort(all(v));
ll mx=0;
for(auto [a, b]:v)
{
// cout<<a<<" "<<b<<" "<<mx<<"+++\n";
if(a>mx)
{
ans+=(b-a+1);
}
else
{
if(b>mx) ans+=(b-mx);
}
mx=max(mx, b);
}
}
cout<<ans<<"\n";
return 0;
}
