#include <bits/stdc++.h>
#define ll long long
#define ull unsigned long long
#define lsb(x) (x & (-x))
using namespace std;
const ll INF = 1e18 + 5;
inline ll gcd(ll a, ll b) {
while(b > 0) {
ll r = a % b;
a = b;
b = r;
}
return a;
}
int main() {
#if 0
ifstream cin("A.in");
ofstream cout("A.out");
#endif
int n, i;
ios::sync_with_stdio(false);
cin.tie(0), cout.tie(0);
ll a, b;
cin >> n >> a >> b;
ll g = gcd(a, b + 1), per = INF;
if(a / g <= INF / b) {
per = (a / g);
per *= b;
}
vector < pair <ll, ll> > segm;
for(i = 0; i < n; i++) {
ll l, r;
cin >> l >> r;
if(r - l + 1 >= per) {
cout << per;
return 0;
}
if(l == r) {
l %= per, r %= per;
segm.push_back({l, r});
}
else {
l %= per, r %= per;
if(l >= r) {
segm.push_back({l, per - 1});
segm.push_back({0, r});
}
else {
segm.push_back({l, r});
}
}
}
sort(segm.begin(), segm.end(), [&](const pair <ll, ll> &x, const pair <ll, ll> &y) {
if(x.first == y.first) return x.second > y.second;
return x.first < y.first;
});
ll last = -1, ans = 0;
for(auto &it : segm) {
if(last < it.first) {
ans += it.second - it.first + 1;
last = it.second;
}
else if(it.second >= last) {
ans += it.second - last;
last = it.second;
}
}
cout << ans;
return 0;
}
