//#define NDEBUG
#include <bits/stdc++.h>
#include <bits/extc++.h>
#define StarBurstStream ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define iter(a) a.begin(), a.end()
#define riter(a) a.rbegin(), a.rend()
#define lsort(a) sort(iter(a))
#define gsort(a) sort(riter(a))
#define pb(a) push_back(a)
#define eb(a) emplace_back(a)
#define pf(a) push_front(a)
#define pob pop_back()
#define pof pop_front()
#define mp(a, b) make_pair(a, b)
#define F first
#define S second
#define mt make_tuple
#define gt(t, i) get<i>(t)
#define iceil(a, b) ((a + b - 1) / b)
#define tomax(a, b) (a = max(a, b))
#define printv(a, b) {bool pvaspace=false; \
for(auto pva : a){ \
if(pvaspace) b << " "; pvaspace=true;\
b << pva;\
}\
b << "\n";}
//#define TEST
using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using pdd = pair<ld, ld>;
using tiii = tuple<int, int, int>;
const ll MOD = 1000000007;
const ll MAX = 2147483647;
template<typename A, typename B>
ostream& operator<<(ostream& o, pair<A, B> p){
return o << '(' << p.F << ',' << p.S << ')';
}
int main(){
StarBurstStream
int n;
cin >> n;
ll a, b;
cin >> a >> b;
ll x = a / __gcd(a, b + 1);
ll t = x > iceil((1LL << 60), b) ? (1LL << 60) : x * b;
vector<pll> e;
for(int i = 0; i < n; i++){
ll l, r;
cin >> l >> r;
if(r - l + 1 >= t){
cout << t << "\n";
return 0;
}
if(l % t <= r % t){
e.eb(mp(l % t, 1));
e.eb(mp(r % t + 1, 0));
}
else{
e.eb(mp(l % t, 1));
e.eb(mp(t, 0));
e.eb(mp(0, 1));
e.eb(mp(r % t + 1, 0));
}
}
// cerr << t << "\n";
ll ans = 0, lst = -1;
int cnt = 0;
lsort(e);
for(pll i : e){
// cerr << i.F << " " << i.S << " " << lst << "\n";
if(i.S){
cnt++;
if(lst == -1) lst = i.F;
}
else{
cnt--;
if(cnt == 0){
// cerr << "test " << lst << " " << i.F << "\n";
ans += i.F - lst;
lst = -1;
}
}
// cerr << cnt << " " << ans << "\n";
}
cout << ans << "\n";
return 0;
}
