哈希

#include<bits/stdc++.h>
using namespace std;
const int MOD = 2333;
int ans = 0, num, mo;
vector<int> hash[MOD + 10];

void insert(int a) {
    mo = a % MOD;
    for (int i = 0; i < hash[mo].size(); i++)
        if (hash[mo][i] == a)
            return;
    ans++;
    hash[mo].push_back(a);
}

int main() {
    int n;
    int a;
    scanf("%d", &n);
    for (int i = 1; i <= n; i++)
        scanf("%d", &a), insert(a);
    printf("%d\n", ans);
    return 0;
}