#pragma GCC optimize("Ofast")
#pragma GCC target("avx2")

#define rd_init() char*rp=({char*mmap();mmap(0l,1l<<25,1,2,0,0ll);})
#define rd() ({int _v=0,_c;while(_c=*rp++-48,_c>=0)_v=_v*10+_c;_v;})
#define rd_signed() ({int _s=*rp=='-'&&++rp,_v=rd();_s?-_v:_v;})
#define WTHI(v) {unsigned _z=v,_n=0;long _d=0;while(++_n,_d=_d<<8|0x30|_z%10,_z/=10);*(long*)wp=_d;wp+=_n;}
#define WTLO(v) {unsigned _z=v,_n=8;long _d=0;while(_d=_d<<8|0x30|_z%10,_z/=10,--_n);*(long*)wp=_d;wp+=8;}
#define wt(v) ({ulong _v=v;if(_v>=100000000){if(_v>=10000000000000000l){WTHI(_v/10000000000000000l);WTLO(_v/100000000%100000000);}else WTHI(_v/100000000);WTLO(_v%100000000);}else{WTHI(_v);}})
#define repeat(e) for(typeof(e)_=e;_--;)
#define chmin(v,a) (v=v<=a?v:a)
#define chmax(v,a) (v=v>=a?v:a)

typedef unsigned long ulong;

char wbuf[1<<25];

int main(){
	char*wp=wbuf;
	rd_init();
	repeat(rd()){
		int b=(int)2e9;
		int c=-b;
		int d=b;
		int e=c;
		repeat(rd()){
			int v=rd_signed();
			chmin(b,v);
			chmax(c,v);
			if(v>=0){
				chmin(d,v);
			}else{
				chmax(e,v);
			}
		}
		long z;
		if(d&&(b>0||c<0)){
			z=(long)b*(long)c;
		}else{
			z=(long)d*(long)e;
			if(z<0){
				*wp++='-';
				z=-z;
			}
		}
		wt(z);
		*wp++='\n';
	}
	write(1,wbuf,wp-wbuf);
	_exit(0);
}