#include <bits/stdc++.h>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>
using namespace std;
using namespace __gnu_pbds;
#define int long long
//#pragma GCC optimize("Ofast")
//#pragma comment(linker, "/stack:200000000")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4")
#define file(s) freopen(s".in","r",stdin); freopen(s".out","w",stdout);
#define fastio ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define all(x) x.begin(), x.end()
#define sz(s) (int)s.size()
#define pb push_back
#define ppb pop_back
#define mp make_pair
#define s second
#define f first
typedef pair < long long, long long > pll;
typedef pair < int, int > pii;
typedef unsigned long long ull;
typedef vector < pii > vpii;
typedef vector < int > vi;
typedef long double ldb;
typedef long long ll;
typedef double db;
typedef tree<pii, null_type, less<pii>, rb_tree_tag, tree_order_statistics_node_update> ordered_set;
const int dx[] = {1, -1, 0, 0}, dy[] = {0, 0, 1, -1}, block = 555;
const pii base = mp(1171, 3307), Mod = mp(1e9 + 7, 1e9 + 9);
const int inf = 1e9, maxn = 4e5 + 148, mod = 1e9 + 7, N = 2e5 + 11;
const db eps = 1e-12, pi = 3.14159265359;
const ll INF = 1e18;
int n, a, b, l, r;
vpii v;
main () {
fastio
scanf("%lld%lld%lld", &n, &a, &b);
int g = __gcd(a, b + 1);
a /= g;
if (a <= 2*INF / b)
a *= b;
else
a = 2*INF;
while (n--) {
scanf("%lld%lld", &l, &r);
if (r - l + 1 >= a) {
cout << a << endl;
return 0;
}
l %= a;
r %= a;
if (l > r) {
v.pb({0ll, 1ll});
v.pb({r + 1, -1ll});
v.pb({l, 1ll});
v.pb({a, -1ll});
} else {
v.pb({l, 1ll});
v.pb({r + 1, -1ll});
}
}
sort(all(v));
int ans = 0, cur = 0;
for (int i = 0; i < sz(v); ++i) {
if (cur > 0)
ans += v[i].f - v[i - 1].f;
cur += v[i].s;
}
cout << ans << endl;
}
