#include<iostream>
#include<cstdio>
using namespace std;
const int MAXN=1e4+10; 
int n,t,cnt;
int a[MAXN];
bool flag;
int main(){
    freopen("sequence.in","r",stdin);
    freopen("sequence.out","w",stdout);
    cin>>t;
    while(t>0){
        bool flag=false;
        cnt=1;
        t--;
        cin>>n;
        for(int i=1;i<=n;i++){
            cin>>a[i];
        }
        for(int i=2;i<=n-1;i++){
            int mid=i;
            for(int l=mid-1;l>=1;l--){
                for(int r=mid+1;r<=n;r++){
                    if(a[mid]-a[l]==a[r]-a[mid]){
                        flag=true;
                        break;
                    }
                }
            }
            if(flag)break;
        }
        if(flag)cout<<"Y"<<endl;
        else cout<<"N"<<endl;
    }
    return 0;
}