#include <bits/stdc++.h>
using namespace std;
#define MASK(x) (1LL << (x))
#define BIT(x, i) (((x) >> (i)) & 1)
#define ALL(x) (x).begin(), (x).end()
#define REP(i, n) for (int i = 0, _n = n; i < _n; ++i)
#define FOR(i, a, b) for (int i = (a), _b = (b); i <= _b; ++i)
#define FORD(i, a, b) for (int i = (a), _b = (b); i >= _b; --i)
#define FORE(it, s) for (__typeof(s.begin()) it = (s).begin(); it != (s).end(); ++it)
#define TIME (1.0 * clock() / CLOCKS_PER_SEC)
#define file(TASK) \
if (fopen(TASK ".inp", "r")) { \
freopen(TASK ".inp", "r", stdin); \
freopen(TASK ".out", "w", stdout); \
}
template <class U, class V> bool maximize(U &A, const V &B) { return (A < B) ? (A = B, true) : false; }
template <class U, class V> bool minimize(U &A, const V &B) { return (A > B) ? (A = B, true) : false; }
int N;
#define int long long
const int INF = 2e18;
long long A, B;
void process(void) {
cin >> N >> A >> B;
int period = A / __gcd(A, B + 1);
if(INF / B >= period) period *= B;
else period = INF;
vector <pair <int, int>> events;
while(N--) {
int l, r; cin >> l >> r;
if(r - l + 1 >= period) return void(cout << period);
l %= period, r %= period;
if(l <= r) {
events.push_back(make_pair(l, 0));
events.push_back(make_pair(r, 1));
} else {
events.push_back(make_pair(0, 0));
events.push_back(make_pair(r, 1));
events.push_back(make_pair(l, 0));
events.push_back(make_pair(period - 1, 1));
}
}
sort(ALL(events));
int ans = 0, Leftmost = -1, cnt = 0;
for (auto [x, i] : events) {
if(i == 0) {
cnt++;
if(Leftmost == -1) Leftmost = x;
} else {
cnt--;
if(cnt == 0) {
ans += x - Leftmost + 1;
Leftmost = -1;
}
}
}
cout << ans;
}
signed main() {
file("TASK");
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
int test = 1;
// cin >> test;
while(test--) {
process();
cout << '\n';
}
cerr << "Time elapsed: " << TIME << " s.\n";
return (0 ^ 0);
}
