#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll, ll> pll;
typedef pair<int, int> pii;
#define all(x) (x).begin(),(x).end()
#define X first
#define Y second
#define sep ' '
#define endl '\n'
#define SZ(x) ll(x.size())
const ll MAXN = 1e6 + 10;
const ll LOG = 22;
const ll INF = 2e18;
const ll MOD = 1e9 + 7; //998244353; //1e9 + 9;
ll n , A , B , sum , ans , L[MAXN] , R[MAXN];
vector<pll> vec;
int main() {
ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
cin >> n >> A >> B;
A /= __gcd(A , B + 1);
for(int i = 0 ; i < n ; i++){
cin >> L[i] >> R[i];
sum += R[i] - L[i] + 1;
}
if(INF / A <= B) return cout << sum << endl , 0;
A *= B; //cout << A << endl;
for(int i = 0 ; i < n ; i++){
if(R[i] - L[i] + 1 >= A) return cout << A << endl , 0;
L[i] %= A; R[i] %= A;
if(L[i] <= R[i]) vec.push_back({L[i] , R[i]});
else{
vec.push_back({0 , R[i]});
vec.push_back({L[i] , A - 1});
}
}
sort(all(vec));
ll l = 0 , r = -1;
for(pll i : vec){
if(r < i.X){
ans += r - l + 1;
l = INF , r = -1;
}
l = min(l , i.X);
r = max(r , i.Y);
}
cout << ans + r - l + 1 << endl;
return 0;
}
/*
*/
