Go: package main

import (
	"bufio"
	"os"
	"strconv"
	"strings"
	"fmt"
)

var scanner = bufio.NewScanner(os.Stdin)

func main() {
	scanner.Scan()
	n, _ := strconv.Atoi(scanner.Text())
	for i := 0; i < n; i++ {
		scanner.Scan()
		input := strings.Split(scanner.Text(), " ")
		buf := make([]float64, len(input))
		for j := range buf {
			buf[j], _ = strconv.ParseFloat(input[j], 64)
		}
		p1 := complex(buf[0], buf[1])
		p2 := complex(buf[2], buf[3])
		p3 := complex(buf[4], buf[5])
		pk := complex(buf[6], buf[7])
		ps := complex(buf[8], buf[9])
		kin := isAtSameSide(p3, pk, []complex128{p1, p2}) &&
			isAtSameSide(p1, pk, []complex128{p2, p3}) &&
			isAtSameSide(p2, pk, []complex128{p3, p1})
		sin := isAtSameSide(p3, ps, []complex128{p1, p2}) &&
			isAtSameSide(p1, ps, []complex128{p2, p3}) &&
			isAtSameSide(p2, ps, []complex128{p3, p1})
		if (kin || sin) && !(kin && sin) {
			fmt.Println("OK")
		} else {
			fmt.Println("NG")
		}
	}
}

func isAtSameSide(a, b complex128, line []complex128) bool {
	sa := (real(line[1]) - real(line[0]))*(imag(a)-imag(line[0]))+
		(imag(line[1])-imag(line[0]))*(real(line[0])-real(a))
	sb := (real(line[1]) - real(line[0]))*(imag(b)-imag(line[0]))+
		(imag(line[1])-imag(line[0]))*(real(line[0])-real(b))
	return (sa > 0 && sb > 0) || (sa < 0 && sb < 0)
}

C++: #include <iostream>
#include <iomanip>
#include <sstream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <climits>
#include <cfloat>
#include <vector>
#include <string>
#include <stack>
#include <queue>
#include <set>
#include <map>
#include <algorithm>
#include <functional>
#include <utility>
#include <numeric>
#include <iterator>

using namespace std;

typedef long long LL;
typedef unsigned long long ULL;
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<string> VS;
typedef pair<int,int> PII;
typedef vector<PII> VPII;
typedef istringstream ISS;
typedef ostringstream OSS;

#define REP( i, m, n ) for ( int i = (int)( m ); i < (int)( n ); ++i )
#define FOR( v, c ) for ( auto &v : c )
#define EACH( it, c ) for ( auto it = c.begin(); it != c.end(); ++it )
#define ALL( c ) (c).begin(), (c).end()
#define DRANGE( c, p ) (c).begin(), (c).begin() + p, (c).end()

#define PB( n ) push_back( n )
#define MP( a, b ) make_pair( ( a ), ( b ) )
#define EXIST( c, e ) ( (c).find( e ) != (c).end() )

#define fst first
#define snd second

#define DUMP( x ) cerr << #x << " = " << ( x ) << endl
#define DEBUG( x ) cerr << __FILE__ << ":" << __LINE__ << ": " << #x << " = " << ( x ) << endl

#include <complex>
typedef complex<double> Point;
const double EPS = 1e-8;

// 入力ストリームから実数二つをとって Point へ
istream& operator >> ( istream &s, Point &a )
{
	double r, i;
	s >> r >> i;
	a = Point( r, i );
	return s;
}

// 外積（クロス積）
double cross( const Point &a, const Point &b )
{
	return a.real() * b.imag() - a.imag() * b.real();
}

// CCW 関数　a -> b -> c と進むとき、反時計回りなら 1, 直進なら 0, 時計回りなら -1
// include : cross
int ccw( const Point &a, const Point &b, const Point &c )
{
	if ( cross( ( b - a ), ( c - a ) ) < -EPS )
	{
		return -1;
	}
	else if ( EPS < cross( ( b - a ), ( c - a ) ) )
	{
		return 1;
	}
	else
	{
		return 0;
	}
}

// 点 p が多角形 qs の内部にあるか ( Winding Number Algorithm) :TODO
// include : ccw
bool point_in_polygon( const Point &p, const vector<Point> &qs )
{
	const int N = qs.size();
	
	int wn = 0;
	for ( int i = 0; i < N; ++i )
	{
		const Point &s = qs[i], &t = qs[ ( i + 1 ) % N ];
		if ( s.imag() - EPS <= t.imag() && s.imag() - EPS < p.imag() && p.imag() + EPS < t.imag() ) // 上向きの辺
		{
			wn += ccw( s, p, t ) == -1;
		}
		else if ( t.imag() - EPS <= s.imag() && t.imag() - EPS < p.imag() && p.imag() + EPS < s.imag() )
		{
			wn -= ccw( t, p, s ) == -1;
		}
	}
	return wn;
};

int main()
{
	cin.tie( 0 );
	ios::sync_with_stdio( false );

	int n;
	cin >> n;
	REP( i, 0, n )
	{
		vector<Point> tri( 3 );
		REP( j, 0, 3 )
		{
			cin >> tri[i];
		}
		Point s, t;
		cin >> s >> t;

		cout << ( point_in_polygon( s, tri ) ^ point_in_polygon( t, tri ) ? "OK" : "NG" ) << endl;
	}

	return 0;
}

C++: #include<iostream>
#include<vector>
#include<complex>
#include<algorithm>
#include<cmath>
using namespace std;

#define EPS (1e-10)
#define EQ(a,b) (abs((a)-(b)) < EPS)
#define EQV(a,b) (EQ((a).real(),(b).real()) && EQ((a).imag(),(b).imag()))
typedef complex<double> Po;

Po unit(Po p){return p / abs(p);}
  
Po normal(Po p,int m){
  Po x;
  if(!m)x = p * Po(0,1);
  else x = p * Po(0,-1);
  return x;
}

double dot(Po x,Po y){return x.real()*y.real() + x.imag()*y.imag();}

double cross(Po x,Po y){return x.real()*y.imag() - x.imag()*y.real();}

double area(Po a,Po b,Po c){
  return abs(cross(b-a,c-a)/2);
}

bool inter(Po a,Po b,Po c,Po x){
  if( area(a,b,x) + area(b,c,x) + area(c,a,x) > area(a,b,c) +EPS)return false;
  else return true;
}

double heron(double a,double b,double c){
  double s = (a+b+c)/2;
  return sqrt(s*(s-a)*(s-b)*(s-c));
}

class line{
 public:
  Po a,b;

  void set(Po x,Po y){
    a = x;
    b = y;
  }

  bool orth(line l){
    return EQ( dot(a-b,l.a-l.b),0.0);
  }

  bool para(line l){
    return EQ( cross(a-b,l.a-l.b),0.0);
  }

  bool on_line(Po x){
    return EQ( cross(b-a,x-a),0.0);
  }

  double line_dis(Po x){
    return abs(cross(b-a,x-a))/abs(b-a);
  }

  Po line_cp(line l){
    return a + (b-a)*cross(l.b-l.a,l.a-a) /cross(l.b-l.a,b-a);
  }

  bool on_seg(Po x){
    return (abs(a-x) + abs(x-b) < abs(a-b) + EPS);
  }

  double seg_dis(Po x){
    if(dot(b-a,x-a)<EPS)return abs(x-a);
    if(dot(a-b,x-b)<EPS)return abs(x-b);
    return abs(cross(b-a,x-a))/abs(b-a);
  }

  int is_cross(line l){
    return (cross(b-a,l.a-a) * cross(b-a,l.b-a)<EPS) && (cross(l.b-l.a,a-l.a) * cross(l.b-l.a,b-l.a) < EPS);
  }

  Po seg_cp(line l){
    double d = abs(cross(l.b-l.a,a-l.a));
    return a + (b-a)*( d / (d * abs(cross(l.b-l.a,b-l.a))));
  }
};

class polygon{
 public:
  vector<Po> v;
  int o;

  void set(void){
    v.clear();
  }

  void Vadd(Po a){
    if(!v.size())o = 0;
    else if(a.imag() < v[o].imag())o = v.size();
    v.push_back(a);
  }

  void sort(void){
    vector<double> seta;
    Po ot;
    ot.real() = 1.0;
    ot.imag() = 0.0;
    swap(v[0],v[o]);
    o = 0;
    for(int i=1;i<(int)v.size();i++){
      seta.push_back(dot(ot,v[i]-v[0]) / (abs(ot)*abs(v[i]-v[0])) );
    } 
    for(int i=1;i<(int)v.size()-1;i++){
      for(int j=i+1;j<(int)v.size();j++){
	if(seta[i-1] < seta[j-1]){
	  swap(seta[i-1],seta[j-1]);
	  swap(v[i],v[j]);
	}
      }
    }
  }

  bool inter(Po a){
    int c = 0;
    double max = 0;
    Po b;
    line l,s;
    for(int i=0;i<(int)v.size();i++)if(max < v[i].real())max = v[i].real();
    b.real() = max+1;
    b.imag() = a.imag();
    s.set(a,b);
    for(int i=0;i<(int)v.size()-1;i++){
      l.set(v[i],v[i+1]);
      if(s.para(l)){
	l.a.imag() += 1e-6;
	l.b.imag() += 1e-6;
      }
      if(s.is_cross(l))c++;
    }
    l.set(v[(int)v.size()-1],v[0]);
    if(s.para(l)){
      l.a.imag() += 1e-6;
      l.b.imag() += 1e-6;
    }
    if(s.is_cross(l))c++;
    if(c%2)return true;
    else return false;
  }
};

int main(){
  int n;
  Po p1,p2,p3,pk,ps;
  polygon tri;

  cin >> n;

  for(int i=0;i<n;i++){
    cin >> p1.real() >> p1.imag();
    cin >> p2.real() >> p2.imag();
    cin >> p3.real() >> p3.imag();
    cin >> pk.real() >> pk.imag();
    cin >> ps.real() >> ps.imag();
    
    tri.set();
    tri.Vadd(p1);
    tri.Vadd(p2);
    tri.Vadd(p3);
    tri.sort();
    
    if(tri.inter(pk) != tri.inter(ps))cout << "OK" << endl;
    //if(inter(p1,p2,p3,pk) != inter(p1,p2,p3,ps) )cout << "OK" << endl;
    else cout << "NG" << endl;
  }
  
}