/*
* AUTHOR : lo0ker
* Problem : Advertisement 2
* source : https://oj.uz/problem/view/JOI23_ho_t2
*/
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using vi = vector<int>;
using pii = pair<int, int>;
#define pb push_back
#define all(x) begin(x), end(x)
#define sz(x) (int) (x).size()
const int MOD = 1e9+7;
int main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);
int n;
cin >> n;
set<int> s;
int x, e;
for(int i = 0; i < n; i++){
cin >> x >> e;
s.insert(x);
}
cout << sz(s);
return 0;
}
