// READ & UNDERSTAND
// ll, int overflow, array bounds, memset(0)
// special cases (n=1?), n+1 (1-index)
// do smth instead of nothing & stay organized
// WRITE STUFF DOWN
#include <bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define pb push_back
#define all(x) (x).begin(), (x).end()
#define MOD 1000000007
typedef long long ll;
typedef pair <int, int> ii;
typedef pair <ll, ll> pll;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef long double ld;
ll INF=LLONG_MAX;
int const mxn=1e6+5;
ll const MAX=1e18+10;
ll l[mxn],r[mxn];
int main()
{
ios_base::sync_with_stdio(0); cin.tie(0);
//freopen("input.txt","r",stdin); freopen("output.txt","w",stdout);
ll n,a,b;
cin >> n >> a >> b;
ll gcd = __gcd(a,b+1);
ll maxi = a/gcd;
if(__lg(a)+__lg(b)>60){
maxi = MAX;
}else{
maxi = min(maxi*b,MAX);
}
bool all=0;
vector<pll>seg;
for(int i=0; i<n; i++){
cin >> l[i] >> r[i];
if(r[i]-l[i]+1>=maxi)all=1;
l[i]%=maxi; r[i]%=maxi;
if(r[i]>=l[i]){
seg.emplace_back(pll(l[i],r[i]));
}else{
seg.emplace_back(pll((ll)0,r[i]));
seg.emplace_back(pll(l[i],ll(maxi-1)));
}
}
if(all){
cout << maxi << endl;
return 0;
}
sort(all(seg));
ll ans = 0;
ll cur = 0;
for(int i=0; i<(int)seg.size(); i++){
ans += max(ll(0),seg[i].se+1-max(seg[i].fi,cur));
cur = max(seg[i].se+1,cur);
}
cout << ans << endl;
}
