#include <iostream>
#include <vector>
#include <unordered_set>

using namespace std;

int main() {
    int n;
    cin >> n;
    vector<int> v(n);
    
    for (int i = 0; i < n; i++) {
        cin >> v[i];
    }

    unordered_set<int> seen; // To track unique elements
    int db = 0; // Count of unique elements

    for (int i = 0; i < n; i++) {
        // If the element is not in the set, it's unique
        if (seen.find(v[i]) == seen.end()) {
            seen.insert(v[i]); // Add to the set
            db++; // Increment unique count
        }
    }

    cout << db;
    return 0;
}