#include "bits/stdc++.h"
using namespace std;
using i64 = long long;
using u64 = unsigned long long;
using i32 = int;
using u32 = unsigned;
using i16 = short;
using u16 = unsigned short;
using ld = long double;
using ii = pair<int, int>;
void solve() {
/*
t1 < t2
t2 = t1 + Bk
t1 + t1 / B = t1 + Bk + (t1 + Bk) / B mod A
t1 / B = Bk + (t1 + Bk) / B mod A
t1 / B = Bk + t1 / B + k mod A
0 = Bk + k mod A
0 = k(B + 1) mod A
C = AB/gcd(A, B + 1)
t2 = t1 + Ck'
t2 = t1 mod C
*/
int n;
i64 A, B;
cin >> n >> A >> B;
__int128 C = (__int128)A * B / gcd(A, B + 1);
vector<pair<i64, int>> sweep;
for(int i = 0; i < n; ++i) {
i64 l, r;
cin >> l >> r;
if(r - l + 1 >= C) {
sweep.push_back({0, 1});
sweep.push_back({C, -1});
continue;
}
i64 L = l % C, R = r % C;
if(L <= R) {
sweep.push_back({L, 1});
sweep.push_back({R + 1, -1});
} else {
sweep.push_back({L, 1});
sweep.push_back({C, -1});
sweep.push_back({0, 1});
sweep.push_back({R + 1, -1});
}
}
sort(sweep.begin(), sweep.end());
i64 ans = 0;
int abertos = 0;
for(int i = 0; i < (int)size(sweep); ++i) {
auto [x, type] = sweep[i];
if(abertos) ans += x - sweep[i - 1].first;
abertos += type;
}
cout << ans << '\n';
}
int main() {
ios_base :: sync_with_stdio(false);
cin.tie(0);
int t = 1;
//cin >> t;
while(t--) solve();
return 0;
}
