/*
#pragma GCC optimize("Ofast,unroll-loops")
#pragma GCC target("avx2,fma,bmi,bmi2,sse4.2,popcnt,lzcnt")
*/
#include <bits/stdc++.h>
#define taskname ""
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define i64 long long
#define i128 __int128_t
#define isz(x) (int)x.size()
using namespace std;
void solve() {
int n; i64 A, B;
cin >> n >> A >> B;
i64 g = __gcd(A, B + 1);
auto coef = A / g;
i128 mod = i128(1) * coef * B;
map<i128, int> mp;
function<void(i128, i128)> add = [&](i128 l, i128 r) -> void {
if (l > r) {
add(l, mod - 1);
add(0, r);
}
else {
mp[l]++, mp[r + 1]--;
}
};
for (int i = 0; i < n; ++i) {
i64 l, r;
cin >> l >> r;
if (r - l + 1 >= mod) {
cout << (i64)mod << endl;
return;
}
l = l % mod, r = r % mod;
add(l, r);
}
i64 res = 0;
i128 prv = 0, cur = 0;
for (auto [val, cnt] : mp) {
if (cur) res += val - prv;
cur += cnt, prv = val;
}
cout << res << endl;
// cout << coef * B << endl;
}
signed main() {
#ifndef CDuongg
if (fopen(taskname".inp", "r"))
assert(freopen(taskname".inp", "r", stdin)), assert(freopen(taskname".out", "w", stdout));
#else
freopen("bai3.inp", "r", stdin);
freopen("bai3.out", "w", stdout);
auto start = chrono::high_resolution_clock::now();
#endif
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
int t = 1; //cin >> t;
while(t--) solve();
#ifdef CDuongg
auto end = chrono::high_resolution_clock::now();
cout << "\n"; for(int i = 1; i <= 100; ++i) cout << '=';
cout << "\nExecution time: " << chrono::duration_cast<chrono::milliseconds> (end - start).count() << "[ms]" << endl;
#endif
}
