/*
Author : DeMen100ns (a.k.a Vo Khac Trieu)
School : VNU-HCM High school for the Gifted
fuck you adhoc
*/
#include <bits/stdc++.h>
#define int long long
using namespace std;
const int N = 2e5 + 5;
const long long INF = 5e18 + 7;
const int MAXA = 1e9;
const int B = sqrt(N) + 5;
int lcm(int a, int b){
int ans = a / __gcd(a, b);
if (INF / ans < b){
return INF;
}
return ans * b;
}
int calperiod(int A, int B){
/*for(int i = 1; i <= 1000; ++i){
if ((i + i / B) % A == 0 && i % B == 0) return i;
}*/
//lcm(B + 1, A)...
int g = lcm(B + 1, A);
if (g == INF) return INF;
return (g / (B + 1)) * B;
}
void solve()
{
int n, A, B; cin >> n >> A >> B;
int g = calperiod(A, B);
vector <pair<int, int>> range;
for(int i = 1; i <= n; ++i){
int x, y; cin >> x >> y;
if (y - x + 1 >= g){
cout << g << endl;
return;
}
x %= g; y %= g;
if (x <= y) range.push_back({x, y});
else{
range.push_back({x, g - 1});
range.push_back({0, y});
}
}
sort(range.begin(), range.end());
int ans = range[0].second - range[0].first + 1;
int r = range[0].second;
for(int i = 1; i < (int)range.size(); ++i){
if (range[i].second > r){
if (range[i].first > r){
ans += range[i].second - range[i].first + 1;
} else {
ans += range[i].second - r;
}
r = range[i].second;
}
}
cout << ans;
}
signed main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
// freopen("codeforces.inp","r",stdin);
// freopen("codeforces.out","w",stdout);
int t = 1; // cin >> t;
while (t--)
{
solve();
}
}
