//Challenge: Accepted
#include <bits/stdc++.h>
using namespace std;
#ifdef zisk
void debug(){cout << endl;}
template<class T,class ... U> void debug(T a, U ... b){cout << a << " ", debug(b...);}
template<class T> void pary(T l, T r) {
while (l != r) cout << *l << " ", l++;
cout << endl;
}
#else
#define debug(...) 0
#define pary(...) 0
#endif
#define ll long long
#define maxn 100005
#define pii pair<ll, ll>
#define ff first
#define ss second
#define io ios_base::sync_with_stdio(0);cin.tie(0);
ll inf = 1LL<<60;
ll mul(ll a, ll b) {
ll ret = 0;
while (b) {
if (a > inf) return inf;
if (b & 1) ret += a;
a += a;
b >>= 1;
if (ret > inf) return inf;
}
return ret;
}
int main() {
io
ll n, A, B;
cin >> n >> A >> B;
ll cy = mul(A / __gcd(A, B + 1), B);
vector<pii> ev;
for (int i = 0;i < n;i++) {
ll l, r;
cin >> l >> r;
if (r - l + 1 >= cy) {
cout << cy << "\n";
return 0;
}
l %= cy, r %= cy;
if (l <= r) {
ev.push_back({l, 1});
ev.push_back({r + 1, -1});
} else {
ev.push_back({l, 1});
ev.push_back({0, 1});
ev.push_back({r+1, -1});
}
}
ev.push_back({cy, 0});
sort(ev.begin(), ev.end());
ll prv = -1, val = 0, ans = 0;
int siz = ev.size();
for (int i = 0;i < siz;i++) {
int tmp = i;
ll to = val;
while (tmp < siz - 1 && ev[tmp+1].ff == ev[i].ff) {
to += ev[tmp].ss;
tmp++;
}
to += ev[tmp].ss;
if (val) ans += ev[i].ff - prv;
val = to;
prv = ev[i].ff;
i = tmp;
}
cout << ans << "\n";
}
