#include<bits/stdc++.h>
using namespace std;
const int da=536870912;
int main() {
	int n;
	int a[1010];
	while (cin>>n) 
	if(n!=0){
	{
		for (int i=0;i<n;i++) cin>>a[i];
		sort(a,a+n);
		int ans=da;
		for (int i=n-1;i>=0;i--) 
		{
			for (int j=n-1; j>=0; j--) 
			{
				if (i==j) continue;
				int sum=a[i]-a[j];
				int l=0, r=j-1;
				while (r-l>=1) 
				{
					if (a[r]+a[l]==sum&&a[i]!=a[r]&&a[l]!=a[i])
					{
						ans=a[i];
						break;
					} 
					else if(a[r]+a[l]>sum) 
					{
						r--;
					} else l++;	
				}
				if(ans!=da) break;
		}
			if(ans!=da) break;
		}
		if(ans!=da) cout<<ans<<endl;
		else cout<<"No Solution"<<endl;
	}}
	return 0;
}