// Hallelujah, praise the one who set me free
// Hallelujah, death has lost its grip on me
// You have broken every chain, There's salvation in your name
// Jesus Christ, my living hope
#include <bits/stdc++.h>
using namespace std;
template <class T>
inline bool mnto(T& a, T b) {return a > b ? a = b, 1 : 0;}
template <class T>
inline bool mxto(T& a, T b) {return a < b ? a = b, 1: 0;}
#define REP(i, s, e) for (int i = s; i < e; i++)
#define RREP(i, s, e) for (int i = s; i >= e; i--)
typedef long long ll;
typedef long double ld;
#define FI first
#define SE second
typedef pair<int, int> ii;
typedef pair<ll, ll> pll;
typedef tuple<int, int, int> iii;
#define ALL(_a) _a.begin(), _a.end()
#define pb push_back
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<ii> vii;
typedef vector<iii> viii;
#ifndef DEBUG
#define cerr if (0) cerr
#endif
#define INF 1000000005
#define LINF 1000000000000000005ll
#define MAXN 1000005
int n;
ll a, b;
ll l[MAXN], r[MAXN];
ll ans;
int main() {
#ifndef DEBUG
ios::sync_with_stdio(0); cin.tie(0);
#endif
cin >> n >> a >> b;
REP (i, 0, n) {
cin >> l[i] >> r[i];
}
ll g = __gcd(b + 1, a);
__int128 mx = (__int128) a / g * b;
REP (i, 0, n) {
if (r[i] - l[i] + 1 > mx) {
cout << (ll) mx << '\n';
return 0;
}
}
cerr << (ll) mx << '\n';
vector<pll> ev;
REP (i, 0, n) {
l[i] %= mx; r[i] %= mx;
ev.pb({l[i], 1});
if (r[i] >= l[i]) {
ev.pb({r[i] + 1, -1});
} else {
ev.pb({r[i] + mx + 1, -1});
}
cerr << l[i] << ' ' << r[i] << '\n';
}
sort(ALL(ev));
ll p = 0, cur = 0;
for (auto [a, b] : ev) {
cerr << a << ' ' << b << '\n';
if (cur > 0) {
ans += a - p;
}
cur += b;
p = a;
}
cout << ans << '\n';
return 0;
}
