题解

#include <bits/stdc++.h>
using namespace std;
int A[100005],cnt[100005];
int main(){
	int n,ans = 0;
	cin >> n;
	for(int i = 1;i <= n;i++){
		cin >> A[i];
		cnt[A[i]]++;
	}
	for(int i = 1;i <= 100000;i++){
		if(cnt[i] > 0){
			ans++;
		}
	}
	cout<< ans;
	return 0;
}