#include <cstdio>
#include <algorithm>
#include <cstring>
#include <vector>
#include <queue>
#include <map>

#define rep(i, l, r) for(int i=l; i<=r; i++)
#define    dow(i, l, r) for(int i=l; i>=r; i--)
#define travel(x) for(edge *p=fir[x]; p; p=p->n)
#define clr(x,c) memset(x, c, sizeof(x))

#define pb push_back
#define all(x) (x).begin(),(x).end()
#define l(x) Left[x]
#define r(x) Right[x]

using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> Pii;
inline int read()
{
    int x=0,f=0; char ch=getchar();
    while (ch<'0' || '9'<ch) f|=ch=='-', ch=getchar();
    while ('0'<=ch && ch<='9') x=x*10+ch-'0', ch=getchar();
    return f?-x:x;
}

#define maxn 39

int n, k[maxn]; ll A;

int main()
{
    int t=read(); while (t--)
    {
        n=read(); rep(i, 1, n) k[i]=read(); sort(k+1, k+1+n); printf("%d\n", k[n]<0?-k[n]:k[n]);
    }
    return 0;
}