#include <fstream>
#include <map>
using namespace std;
ifstream fi("plana.in");
ofstream fo("plana.out");
int n,g[1001],ans;
class x
{
public:
int a,b;
};
x he;
map <int,x> v;
map <int,x>::iterator cp;
void init()
{
int i,j;
fi>>n;ans=-999999999;v.clear();
for (i=1;i<=n;i++) fi>>g[i];
for (i=1;i<=n;i++)
for (j=1;j<=n;j++)
if (i!=j)
{
he.a=i;he.b=j;
v.insert(pair<int,x> (g[i]+g[j],he));
}
for (i=1;i<=j;i++)
for (j=1;j<=n;j++)
if (i!=j)
{
cp=v.find(g[i]-g[j]);
if (cp!=v.end())
if (cp->second.a!=i&&cp->second.b!=i&&cp->second.a!=j&&cp->second.b!=j)
if (ans<g[i]) ans=g[i];
}
if (ans==-999999999) fo<<"No Solution"<<endl;else fo<<ans<<endl;
}
int main()
{
init();
init();
return 0;
}