// In the name of god
#pragma comment(linker, "/stack:200000000")
#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
template < class T > using ordered_set = tree < T , null_type , less < T > , rb_tree_tag , tree_order_statistics_node_update >;
typedef long long ll;
typedef long double ld;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
#define all(x) (x).begin(),(x).end()
#define lc(x) (x) << 1
#define rc(x) (x) << 1 | 1
#define F first
#define S second
#define fast_io ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define file_io freopen("in.txt" , "r+" , stdin) ; freopen("out.txt" , "w+" , stdout);
#define mp make_pair
ll poww(ll a, ll b, ll md) {
ll ans = 1;
for(; b; b >>= 1, a = a * a % md){
if(b & 1){
ans = ans * a % md;
}
}
return ans % md;
}
const int MAXN = 2e6 + 10;
const int MAXLG = 18;
const int MOD = 1e9 + 7;
const int MOD2 = 998244353;
const ll INF = 2e18 + 10;
ll n, val[MAXN];
ll A, B, ans, l[MAXN], r[MAXN];
vector<ll> vec;
vector<pll> seg;
unordered_map<ll, ll> um;
int main()
{
um.max_load_factor(0.13);
scanf("%lld %lld %lld", &n, &A, &B);
for(ll i = 1; i <= n; i++){
scanf("%lld %lld", l + i, r + i);
}
ll x = A / __gcd(A, B + 1);
if(x > INF / B){
for(ll i = 1; i <= n; i++){
ans += r[i] - l[i] + 1;
}
printf("%lld\n", ans);
return 0;
}
x *= B;
vec.push_back(0);
vec.push_back(x);
for(ll i = 1; i <= n; i++){
if(r[i] - l[i] + 1 >= x){
printf("%lld\n", x);
return 0;
}
ll L = l[i], R = r[i];
L %= x;
R %= x;
vec.push_back(L);
vec.push_back(R + 1);
if(L > R){
seg.push_back(mp(L, x - 1));
seg.push_back(mp(0, R));
}
else{
seg.push_back(mp(L, R));
}
}
sort(all(vec));
vec.erase(unique(all(vec)), vec.end());
for(int i = 0; i < (int)vec.size(); i++){
um[vec[i]] = i;
}
for(auto v : seg){
ll ind1;
ll ind2;
ind1 = um[v.F];
ind2 = um[v.S + 1];
val[ind1]++;
val[ind2]--;
}
for(ll i = 1; i < (ll)vec.size(); i++){
val[i] += val[i - 1];
}
for(ll i = 0; i < (ll)vec.size() - 1; i++){
if(val[i]){
ans += vec[i + 1] - vec[i];
}
}
printf("%lld\n", ans);
}
