#pragma GCC optimization ("unroll-loops")
//#pragma GCC optimization ("O1, O2, O3, Ofast")
//#pragma GCC optimization ("trapv")
//#pragma GCC optimization ("sse, sse2, sse3, sse4, sse4.1, sse4.2, avx")
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define max_heap priority_queue<ll>
#define min_heap priority_queue<pair <ll, ll>, vector<pair <ll, ll>>, greater<pair <ll, ll>>>
//#define min_heap priority_queue<ll, vector<ll>, greater<ll>>
#define sariE cin.tie(NULL); cout.tie(NULL); ios_base::sync_with_stdio(false);
#define filE freopen("txt.in.5", "r", stdin); freopen("out1.txt", "w", stdout);
#define endl '\n'
#define md(a) (a % mod + mod) % mod
//cout << setprecision(5) << f;
ll const maxn = 1e5 + 123;
ll const inf = 1e18 + 10;
ll const loG = 23;
ll const mod = 1e9 + 7;
//ll const mod = 998244353;
ll const sq = 350;
ll power(ll a, ll b, ll mod){if (b == 0) return 1; if (b == 1) return a; ll x = power(a, b / 2, mod); return (((x * x) % mod) * (b % 2 ? a : 1)) % mod;}
ll n, a, b, k, ans;
//set <pair <ll, ll>> st;
vector <pair <ll, ll>> arr;
int main(){
sariE;// filE;
cin >> n >> a >> b;
k = a / __gcd(a, (b + 1));
k = k * b;
//cout << k << endl;
//cout << "k is " << k << endl;
for (int i = 1; i < n + 1; i++){
ll l, r; cin >> l >> r;
if (r - l + 1 > k)
arr.push_back({0, k - 1});
else{
ll baz1 = l % k, baz2 = r % k;
//cout << "baze ha " << baz1 << ' ' << baz2 << endl;
if (baz1 <= baz2){
arr.push_back({baz1, baz2});
//setter(baz1, baz2 + 1, 1, 0, 0, inf);
}
else{
arr.push_back({baz1, k - 1});
arr.push_back({0, baz2});
//setter(baz1, k, 1, 0, 0, inf);
//setter(0, baz2 + 1, 1, 0, 0, inf);
}
}
//for (ll j = l; j <= r; j++)
// st.insert({f1(j), f2(j)});
}
sort(arr.begin(), arr.end());
ll mx = arr[0].second; ans += mx - arr[0].first + 1;
//cout << "mx is " << mx << endl;
//cout << arr[0].first << ' ' << arr[0].second << endl;
for (int i = 1; i < arr.size(); i++){
auto p = arr[i];
//cout << "mx is " << mx << endl;
//cout << p.first << ' ' << p.second << endl;
if (mx < p.first){
//cout << "A " << mx << endl;
ans += p.second - p.first + 1;
mx = p.second;
continue;
}
if (p.first <= mx && mx < p.second){
//cout << "B " << mx << endl;
ans += p.second - mx;
mx = p.second;
continue;
}
}
cout << ans << endl;
// //cout << st.size() << endl;
}
