#include<cstdio>

 #include<cstring>

 #include<string>

 #include<cmath>

 #include<iostream>

 #include<algorithm>

 #include<map>

 #include<set>

 #include<queue>

 #include<vector>

 using namespace std;

 typedef long long ll;

 typedef unsigned int uint;

 typedef unsigned long long ull;

 typedef pair<int,int> PII;

 typedef vector<int> VI;

 #define fi first

 #define se second

 #define MP make_pair

 const int N=;

 int a[N],n,cas;

 int read()

 {

    int v=,f=;

    char c=getchar();

    while(c<||<c) {if(c=='-') f=-; c=getchar();}

    while(<=c&&c<=) v=(v<<)+v+v+c-,c=getchar();

    return v*f;

 }

 int main()

 {

  // freopen("1.in","r",stdin);

   //freopen("1.out","w",stdout);

   scanf("%d",&cas);

   for(int i=;i<=cas;i++)

   {

    scanf("%d",&n);

    for(int j=;j<=n;j++) scanf("%d",&a[j]);

    int t=sqrt(abs(a[n]-a[]));

    printf("%d\n",t);

   }

   return ;

 }