#include<bits/stdc++.h>
#define tm (tl + tr)/2
#define inf 1100000000000000000
#define ll long long
using namespace std;
struct tre{
bool lazy;
ll sum;
ll L,R;
tre() {
lazy = sum = L = R = 0;
}
};
vector<tre>t(1);
void push(ll v,ll tl,ll tr,ll L,ll R) {
if (t[v].lazy) {
t[L].lazy = t[R].lazy = 1;
t[L].sum = tm - tl+1;
t[R].sum = tr - tm;
t[v].lazy = 0;
}
}
void upd(ll v,ll tl,ll tr,ll l,ll r) {
if (l > tr || r < tl || t[v].lazy) return;
if (l <= tl && r >= tr) {
t[v].lazy = 1;
t[v].sum = tr - tl + 1;
return;
}
if (t[v].L == 0) {
t[v].L = t.size();
t.push_back(tre());
}
if (t[v].R == 0) {
t[v].R = t.size();
t.push_back(tre());
}
push(v,tl,tr,t[v].L,t[v].R);
upd(t[v].L,tl,tm,l,r);
upd(t[v].R,tm+1,tr,l,r);
t[v].sum = t[ t[v].L ].sum + t[ t[v].R ].sum;
}
main() {
ios::sync_with_stdio(false);
ll n,a,b;
cin >> n >> a >> b;
ll m = a/(__gcd(a,b+1));
if (m > inf/b) m = inf;
else m*=b;
vector<pair<ll,ll> > v;
for (ll l,r;n--;) {
cin >> l >> r;
if (r - l + 1 >= m) {
cout << m <<'\n';
exit(0);
}
l%=m;
r%=m;
if (l < 0) l+=m;
if (r < 0) r+=m;
if ( l <= r) {
v.push_back({l,r});
// upd(0,0,m-1,l,r);
}
else {
v.push_back({0,r});
v.push_back({l,m-1});
// upd(0,0,m-1,l,m-1);
// upd(0,0,m-1,0,r);
}
}
sort(v.begin(),v.end());
ll st = 0, en = -1,ans = 0;
for (auto i : v) {
ll x = i.first, y =i.second;
if (y <= en) continue;
if (x > en) {
ans += y - x + 1;
st = x;
en = y;
}
else {
ans += y - en;
st = x;
en = y;
}
}
cout << ans;
}
