import java.util.*;
public class Main { 
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        Set<Integer> visited = new HashSet<>();
        int cnt = 0;
        while(n > 0) {
          n--;
          int num = sc.nextInt();
          if(visited.contains(num)) continue;
          visited.add(num);
          cnt++;
        }
        System.out.println(cnt);
    }
} import java.util.*; util.* java public class Main { 
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        Set<Integer> visited = new HashSet<>();
        int cnt = 0;
        while(n > 0) {
          n--;
          int num = sc.nextInt();
          if(visited.contains(num)) continue;
          visited.add(num);
          cnt++;
        }
        System.out.println(cnt);
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        Set<Integer> visited = new HashSet<>();
        int cnt = 0;
        while(n > 0) {
          n--;
          int num = sc.nextInt();
          if(visited.contains(num)) continue;
          visited.add(num);
          cnt++;
        }
        System.out.println(cnt);
    } main {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        Set<Integer> visited = new HashSet<>();
        int cnt = 0;
        while(n > 0) {
          n--;
          int num = sc.nextInt();
          if(visited.contains(num)) continue;
          visited.add(num);
          cnt++;
        }
        System.out.println(cnt);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc Set<Integer> visited = new HashSet<>(); visited new HashSet<>() int cnt = 0; cnt 0 while(n > 0) {
          n--;
          int num = sc.nextInt();
          if(visited.contains(num)) continue;
          visited.add(num);
          cnt++;
        } n > 0 n 0 {
          n--;
          int num = sc.nextInt();
          if(visited.contains(num)) continue;
          visited.add(num);
          cnt++;
        } n-- n int num = sc.nextInt(); num sc.nextInt() sc.nextInt sc if(visited.contains(num)) continue; visited.contains(num) visited.contains visited num continue; visited.add(num) visited.add visited num cnt++ cnt System.out.println(cnt) System.out.println System.out System System.out cnt String[] args args public class Main { 
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        Set<Integer> visited = new HashSet<>();
        int cnt = 0;
        while(n > 0) {
          n--;
          int num = sc.nextInt();
          if(visited.contains(num)) continue;
          visited.add(num);
          cnt++;
        }
        System.out.println(cnt);
    }
} public class Main { 
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        Set<Integer> visited = new HashSet<>();
        int cnt = 0;
        while(n > 0) {
          n--;
          int num = sc.nextInt();
          if(visited.contains(num)) continue;
          visited.add(num);
          cnt++;
        }
        System.out.println(cnt);
    }
} Main
import java.util.*;
public class Main { 
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        Set<Integer> visited = new HashSet<>();
        int cnt = 0;
        while(n > 0) {
          n--;
          int num = sc.nextInt();
          if(visited.contains(num)) continue;
          visited.add(num);
          cnt++;
        }
        System.out.println(cnt);
    }
}