#include<bits/stdc++.h>
using namespace std;

void solve(){
    int n,sum=0,i,bin=11;
    cin>>n;
    int arr[n];
    for(int i=0;i<n;i++){
        cin>>arr[i];
    }
    for(int i=0;i<n-1;i++){
        for(int j=i+1;j<n-1;j++){
            sum = arr[i]+arr[j];
        }
    }
    sum = bin;
    int product = bin%10;
    cout<<product<<endl;
}
int main(){
    int t;
    cin>>t;
    while(t--){
        solve();
    }
    return 0;
}