#include<bits/stdc++.h> using namespace std; int main(){ int n; cin>>n; set<int>v; int ccin; for(int i=1;i<=n;i++){ cin>>ccin; v.insert(ccin); } cout<<v.size()<<endl; for(auto a:v){ cout<<a<<" "; } return 0; }

a

千万别点题，不然会被笑s

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