#include <bits/stdc++.h>
#define L(i, j, k) for(int i = (j); i <= (k); i++)
#define R(i, j, k) for(int i = (j); i >= (k); i--)
#define ll long long
#define sz(a) ((int) a.size())
#define all(a) a.begin(), a.end()
#define vi vector<ll>
#define pb emplace_back
#define me(a, x) memset(a, x, sizeof(a))
#define fst first
#define snd second
#define ii pair<ll, ll>
using namespace std;
int main(){
ios::sync_with_stdio(false);
cin.tie(nullptr);
int n;cin>>n;
vi x(n),e(n);
L(i,0,n-1)cin>>x[i]>>e[i];
set<int>s;
L(i,0,n-1){
s.insert(x[i]);
}
cout<<sz(s);
}
