#pragma GCC optimize("Ofast")
#include<bits/stdc++.h>
using namespace std;
#define pb push_back
#define fi first
#define se second
#define mp make_pair
#define all(a) a.begin(),a.end()
#define sz(a) (int)(a.size())
#define lb lower_bound
#define ub upper_bound
#define owo ios_base::sync_with_stdio(0);cin.tie(0);
#define MOD (ll)(1e9+7)
#define INF (ll)(1e18)
#define debug(...) fprintf(stderr, __VA_ARGS__),fflush(stderr)
#define time__(d) for(long blockTime = 0; (blockTime == 0 ? (blockTime=clock()) != 0 : false);\
debug("%s time : %.4fs\n", d, (double)(clock() - blockTime) / CLOCKS_PER_SEC))
typedef long long int ll;
typedef long double ld;
typedef pair<ll,ll> PII;
typedef pair<int,int> pii;
typedef vector<vector<int>> vii;
typedef vector<vector<ll>> VII;
ll gcd(ll A,ll B) {if(!B)return A;return gcd(B,A%B);}
int main()
{
ll n,a,b;
cin>>n>>a>>b;
ll C = a/gcd(a,b+1) > INF/b?INF+1:(a/gcd(a,b+1))*b;
// cout<<C<<'\n';
vector<PII>s;
for(int i=0;i<n;i++){
ll l,r;
cin>>l>>r;
if(r-l+1 > C){cout<<C;return 0;}
l%=C;
r%=C;
if(r >= l){
s.pb({l,r});
}else{
s.pb({l,C-1});
s.pb({0,r});
}
}
sort(all(s));
ll ans = 0;
ll lf = 0;
ll rg = -1;
for(int i=0;i<sz(s);i++){
//cout<<s[i].fi<<" "<<s[i].se<<'\n';
if(s[i].fi > rg){
ans+=rg-lf+1;
lf = s[i].fi;
rg = s[i].se;
if(i == sz(s)-1)ans+=rg-lf+1;
}else{
rg = max(rg,s[i].se);
if(i == sz(s)-1)ans+=rg-lf+1;
}
//cout<<ans<<'\n';
}
cout<<ans<<'\n';
}
