#include<bits/stdc++.h>
using namespace std;
#define int long long
#define pii pair<int,int>
#define fi first
#define se second
const int N = 2e3+5;
int n,a,b,l,r;
vector<pii>loj;
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin >> n >> a >> b;
a /= __gcd(a,b+1);
int cycle;
if(a <= LLONG_MAX/b) cycle = a*b;
else cycle = 4e18;
for(int i = 1; i <= n; i++){
cin >> l >> r;
l %= cycle;
r %= cycle;
if(r-l+1 >= cycle){
cout << cycle;
return 0;
}
if(l <= r) loj.push_back({l,r});
else{
loj.push_back({l,cycle-1});
loj.push_back({0,r});
}
}
sort(loj.begin(),loj.end());
l = loj[0].fi;
r = loj[0].se;
int ans = 0;
for(int i = 1; i < loj.size(); i++){
if(loj[i].fi > r){
ans += r-l+1;
l = loj[i].fi;
r = loj[i].se;
}
else r = max(r,loj[i].se);
}
ans += r-l+1;
cout << ans;
}
