#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef vector<int> veci;
typedef vector<ll> vecll;
#define mp make_pair
#define fi first
#define se second
// debug needs a semicolon !!!
#define debug(x) cerr<<# x<<" is "<<x<<'\n'
#define vec vector
int main() {
ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
int n;
cin >> n;
set<int> s;
while (n--) {
int x, USELESS;
cin >> x >> USELESS;
s.insert(x);
}
cout << s.size();
return 0;
}
