#include <bits/stdc++.h>
// #include <ext/pb_ds/assoc_container.hpp>
// #include <ext/pb_ds/trie_policy.hpp>
// #include <ext/rope>
using namespace std;
// using namespace __gnu_cxx;
// using namespace __gnu_pbds;
void Hollwo_Pelw();
signed main(){
#ifndef hollwo_pelw_local
if (fopen(".inp", "r"))
assert(freopen(".inp", "r", stdin)), assert(freopen(".out", "w", stdout));
#else
auto start = chrono::steady_clock::now();
#endif
cin.tie(0), cout.tie(0) -> sync_with_stdio(0);
int testcases = 1;
// cin >> testcases;
for (int test = 1; test <= testcases; test++){
// cout << "Case #" << test << ": ";
Hollwo_Pelw();
}
#ifdef hollwo_pelw_local
auto end = chrono::steady_clock::now();
cout << "\nExcution time : " << chrono::duration_cast<chrono::milliseconds> (end - start).count() << "[ms]" << endl;
#endif
}
/*
t = z * b + y
0 <= y < b
x = (z * (b + 1) + y) % a
y1 == y2
((z1 - z2) * (b + 1)) % a == 0
b = 1e18
b >= 1e12 -> z <= 1e6
*/
#define int long long
const int N = 1e6 + 5, inf = (int) 1e18 + 7;
int n, a, b, l[N], r[N];
void Hollwo_Pelw(){
cin >> n >> a >> b;
int f = a / __gcd(a, b + 1), p = inf / f >= b ? f * b : inf;
vector<pair<int, int>> v;
for (int i = 1, l, r; i <= n; i++) {
cin >> l >> r;
if (r - l + 1 >= p)
return cout << p, (void) 0;
l %= p, r %= p;
if (l > r) {
v.emplace_back(l, p - 1);
v.emplace_back(0, r);
} else {
v.emplace_back(l, r);
}
}
sort(v.begin(), v.end());
int res = 0, curl = 0, curr = -1;
for (auto [l, r] : v) {
if (curl > r || l > curr) {
res += curr - curl + 1;
curl = l, curr = r;
}
curl = min(curl, l), curr = max(curr, r);
}
res += curr - curl + 1;
cout << res << '\n';
}
