#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define rep(a) rep1(i,a)
#define rep1(i,a) rep2(i,0,a)
#define rep2(i,b,a) for(int i=(b); i<((int)(a)); i++)
#define rep3(i,b,a) for(int i=(b); i>=((int)(a)); i--)
#define all(a) a.begin(),a.end()
#define pii pair<int,int>
#define pll pair<ll,ll>
#define pb push_back
#define mp make_pair
#define sz(a) ((int)a.size())
#define pow2(x) (1ll<<(x))
#define ceiling(a,b) (((a)+(b)-1)/(b))
#define eps 1e-9
#define print0(a) cout << (a) << ' '
#define print1(a) cout << (a) << '\n'
#define print2(a,b) cout << (a) << ' ',print1(b)
#define print3(a,b,c) cout << (a) << ' ',print2(b,c)
#define print4(a,b,c,d) cout << (a) << ' ',print3(b,c,d)
using namespace std;
const int maxn=1000005;
int n;
ll x,y,inf=1e18,mod=-1,minl=4e18,maxr=-1,ans=0;
struct segment{ll l,r;}seg[maxn],seg1;
bool comp(segment i, segment j){return i.l<j.l;}
vector<segment> vec;
int main(){
ios_base::sync_with_stdio(0),cin.tie(0);
cin >> n >> x >> y;
if(x/__gcd(y+1,x)<=inf/y) mod=x/__gcd(y+1,x)*y;
rep(n) cin >> seg[i].l >> seg[i].r;
rep(n){
if(mod>=0){
if(seg[i].r/mod==seg[i].l/mod){
seg[i].l%=mod;
seg[i].r%=mod;
vec.pb(seg[i]);
}
else{
seg[i].l%=mod;
seg[i].r%=mod;
if(seg[i].r>=seg[i].l){
print1(mod);
return 0;
}
seg1.l=seg[i].l,seg1.r=mod-1;
vec.pb(seg1);
seg1.l=0,seg1.r=seg[i].r;
vec.pb(seg1);
}
}
else{
vec.pb(seg[i]);
}
}
sort(all(vec),comp);
for(auto seg2: vec){
if(maxr>=0){
if(seg2.l>maxr){
ans+=maxr-minl+1;
minl=seg2.l,maxr=seg2.r;
}
}
minl=min(minl,seg2.l),maxr=max(maxr,seg2.r);
}
ans+=maxr-minl+1;
print1(ans);
return 0;
}
