#include <bits/stdc++.h>
#pragma GCC target ("avx,avx2,fma")
#pragma GCC optimize ("O2")
#pragma GCC optimize ("unroll-loops")
#define X first
#define Y second
#define debug(x) cerr << #x << ": " << x << endl;
#define endl '\n'
#define pb push_back
#define rep(i,l,r) for (int i=l; i<r; i++)
#define repr(i,r,l) for (int i=r; i>=l; i--)
using namespace std;
typedef long long ll;
typedef pair<ll,ll> pll;
const long long int N=5e2+20,mod = 1e9+7,inf=1e18;
inline int mkay(int a,int b){
if (a+b >= mod) return a+b-mod;
return a+b;
}
ll gcd(ll a,ll b){
if (!b) return a;
if (b < a) swap(a,b);
return gcd(a,b%a);
}
int main(){
ios :: sync_with_stdio(0); cin.tie(0);
int n;
ll a,b,z;
cin >> n >> a >> b;
a /= gcd(a,b+1);
debug(gcd(4,6));
if (b >= (inf+a-1)/a) z = inf+1;
else z = a*b;
set<pll> st;
rep(i,0,n){
ll l,r;
cin >> l >> r;
if (r-l+1 >= z){
cout << z;
return 0;
}
if (r%z < l%z){
auto it = st.upper_bound({l%z,0});
while(it != st.end()){
st.erase(it);
it = st.upper_bound({l%z,0});
}
st.insert({l%z,z});
st.insert({0,r%z+1});
}
else{
st.insert({l%z,r%z+1});
}
}
pll p = {1,-1};
ll ans = 0;
for(pll q : st){
if (q.X >= p.X && q.Y <= p.Y)
continue;
if (q.X <= p.Y){
ans += q.Y-p.Y;
p.Y = q.Y;
continue;
}
p = q;
ans += p.Y-p.X;
}
cout << ans;
return 0;
}
