#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ld long double
#define u128 unsigned __int128
#define i128 __int128
#define len(x) (int)x.size()
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define pb push_back
#define eb emplace_back
#define mt make_tuple
#define mp make_pair
#define pii pair<int, int>
#define pll pair<ll, ll>
#define pli pair<ll, int>
#define pil pair<int, ll>
#define ff first
#define ss second
const ll inf = 9e18;
const int iinf = 2e9;
const int N = 1e5;
const ll MOD = 1e9 + 7;
void solution(){
int n; ll a, b; cin >> n >> a >> b;
ll s = 0, mx_len = 0;
vector<ll> l(n), r(n);
for (int i = 0; i < n; ++i){
cin >> l[i] >> r[i];
s += (r[i] - l[i] + 1);
mx_len = max(mx_len, r[i] - l[i] + 1);
}
if (s <= (int)1e6){
set<pair<ll, ll>> st;
for (int i = 0; i < n; ++i){
for (ll t = l[i]; t <= r[i]; ++t){
ll x = (t + (t / b)) % a;
ll y = t % b;
st.insert({x, y});
}
}
cout << len(st);
}
}
signed main(/* Kurmankul Nurislam */){
//freopen("fcolor.in", "r", stdin);
//freopen("fcolor.out", "w", stdout);
cin.tie(nullptr) -> sync_with_stdio(false);
int t = 1;
//cin >> t;
while (t--){
solution();
//cout << '\n';
}
}
