输出很好玩

#include<bits/stdc++.h>
using namespace std;

int main()
{
    int n;
    cin >> n;
    int a[n];
    for (int i=0;i<n;i++)
        cin >> a[i];
    sort(a,a+n);
    vector<int> b;
    for (int i=0;i<n;i++)
    {
        if (a[i]!=a[i-1])
            b.push_back(a[i]);
    }
    cout << b.size() << endl;
    for_each(b.begin(),b.end(),[](int x){cout << x << ' ';});
	return 0;
}