#include <bits/stdc++.h>
#define pb push_back
#define fst first
#define snd second
#define fore(i,a,b) for(ll i=a,ggdem=b;i<ggdem;++i)
#define SZ(x) ((int)x.size())
#define ALL(x) x.begin(),x.end()
#define mset(a,v) memset((a),(v),sizeof(a))
#define FIN ios::sync_with_stdio(0);cin.tie(0);cout.tie(0)
#define imp(v) for(auto edu:v)cout<<edu<<" "; cout<<"\n"
using namespace std;
typedef long long ll;
typedef pair<ll,ll> ii;
int main(){FIN;
ll n; cin>>n;
vector<ii>a(n),b;
fore(i,0,n)cin>>a[i].fst>>a[i].snd;
sort(ALL(a));
fore(i,0,n){
if(SZ(b)&&b.back().fst==a[i].fst)b.pop_back();
b.pb(a[i]);
}
cout<<SZ(b)<<"\n";
return 0;
}
