#include <bits/stdc++.h>
//#pragma GCC optimize("unroll-loops")
//#pragma GCC optimize("-O3")
//#pragma GCC optimize("Ofast")
//#pragma GCC optimize("fast-math")
//#pragma GCC optimize("no-stack-protector")
#define ft first
#define sd second
#define all(x) x.begin(),x.end()
#define sz(x) ((int)x.size())
#define pll pair<ll, ll>
#define MP make_pair
#define PB push_back
using namespace std;
typedef long long ll;
//typedef long long __int128;
vector<pll> seg;
int n;
ll A, B;
int main(){
#ifdef _LOCAL
freopen("in.txt","r",stdin);
#else
ios_base::sync_with_stdio(0); cin.tie(0);
#endif // _LOCAL
cin >> n >> A >> B;
ll fi = A;
ll gc = __gcd(A, B + 1);
if (A / gc > ll(2e18) / B)
fi = ll(2e18);
else fi = A / gc * B;
seg.clear();
for (int i = 0; i < n; i++){
ll l, r; cin >> l >> r;
if (r - l + 1 >= fi){
seg.PB(MP(0, fi - 1));
continue;
}
ll vl = ((l - 1) / fi) * fi + fi;
if (vl > r){
vl -= fi;
seg.PB(MP(l - vl, r - vl));
} else {
vl -= fi;
seg.PB(MP(l - vl, fi - 1));
vl += fi;
seg.PB(MP(0ll, r - vl));
}
}
sort(all(seg));
ll lst = -1, ans = 0;
for (pll cr : seg)
if (cr.ft > lst){
ans += cr.sd - cr.ft + 1ll;
lst = cr.sd;
} else {
ans += max(lst, cr.sd) - lst;
lst = max(lst, cr.sd);
}
cout << ans << '\n';
return 0;
}
