#include <bits/stdc++.h> #define ll long long #define endl "\n" #define ios ios_base::sync_with_stdio(0); cout.tie(0); cin.tie(0); using namespace std; int main() { ios int n; cin >> n; ll A, B; cin >> A >> B; ll S = 0; ll val = A * B / __gcd(B - 1, A); map <ll, ll> was; ll l[n], r[n], ans = 0; for (int i = 0; i < n; ++ i) { cin >> l[i] >> r[i]; S += r[i] - l[i] + 1; } if (A > 1e18 / B + 1) { cout << S; return 0; } for (int i = 0; i < n; ++ i) { for (int j = l[i]; j <= r[i]; ++ j) { if (was[j % val]); else ++ ans; was[j % val] = 1; } } cout << ans; return 0; }