本蒟蒻第一次没写出来，看了这篇题解才明白(没脸写题解qwq)

参考这篇文章，写的很好

https://www.luogu.com.cn/article/koqj03r3

C++ 代码

#include <iostream>
#define int long long

using namespace std;

int t;

signed main(){
    cin>>t;
    while (t--){
        int n;
        cin>>n;
        if (n%3)  cout<<n<<endl;
        else cout<<n*2<<endl;
    }
    return 0;
}