月赛div2第3题，0分，求大佬看下！

#include <iomanip>
#include <ios>
#include <iosfwd>
#include <iostream>
#include <istream>
#include <ostream>
#include <queue>
#include <set>
#include <algorithm>
#include <sstream>
#include <stack>
#include <stdexcept>
#include <streambuf>
#include <string>
#include <algorithm>
#include <vector>
#include <cwchar>
#include <cwctype>
#include <cstdio>
using namespace std;
long long n,a[10000001];
long long gcd(long long a, long long b){
   long long da=max(a,b);
   long long xiao=min(a,b);
     if(da%xiao==0)
        return xiao;
     else
         return gcd(xiao,da%xiao);
 }
long long lcm(long long a, long long b){
     return a*b/gcd(a,b);
}
long long maxn=-1;
int main() {
    cin>>n;
    for(int i=1;i<=n;++i){
        cin>>a[i];
    }
    for(int i=1;i<=n;++i){
        for(int j=i+1;j<=n;++j){
           
            if(a[i]+a[j]+gcd(a[i],a[j])==lcm(a[i],a[j]) && a[i]+a[j]>maxn)
                maxn=a[i]+a[j]+lcm(a[i],a[j]);
        }
    }
    
    cout<<maxn;
    return 0;
}