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++: #define _CRT_SECURE_NO_WARNINGS

#include <iostream>
#include <cstdio>
#include <cstring>
#include <string>
#include <vector>
#include <cmath>
#include <stack>
#include <queue>
#include <map>
#include <set>
#include <algorithm>
#include <complex>

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef vector<bool> vb;
typedef vector<vb> vvb;
typedef vector<int> vi;
typedef vector<vi> vvi;
#define all(c) (c).begin(), (c).end()
#define loop(i,a,b) for(int i=a; i<int(b); i++)
#define rep(i,b) loop(i,0,b)
#define each(e,c) for(auto& e:c)
#define iter(it,c) for(auto it=c.begin(); it!=c.end(); ++it)

ll const inf = 1<<28;
double const pi = acos(-1);

typedef complex<double> P;
typedef vector<P> L;

double cross(const P& a, const P& b) {
    return imag(conj(a)*b);
}
double dot(const P& a, const P& b) {
    return real(conj(a)*b);
}
int ccw(P a, P b, P c) {
    b -= a; c -= a;
    if (cross(b, c) > 0)   return +1;       // counter clockwise
    if (cross(b, c) < 0)   return -1;       // clockwise
    if (dot(b, c) < 0)     return +2;       // c--a--b on line
    if (norm(b) < norm(c)) return -2;       // a--b--c on line
    return 0;
}
bool intersectSS(const L &s, const L &t) {
    return ccw(s[0],s[1],t[0])*ccw(s[0],s[1],t[1]) <= 0 &&
        ccw(t[0],t[1],s[0])*ccw(t[0],t[1],s[1]) <= 0;
}

P ps[4];
L l;

bool solve(){
    int c=0;
    rep(i,3){
        L m{ps[i],ps[i+1]};
        if(intersectSS(l,m))c++;
    }
    return c==1;
}

int main(){
    int n;cin>>n;
    rep(_,n){
        rep(i,3){
            double x,y;cin>>x>>y;
            ps[i]=P(x,y);
        }
        ps[3]=ps[0];
        double a,b,c,d;
        cin>>a>>b>>c>>d;
        l={P(a,b),P(c,d)};
        cout << (solve()?"OK":"NG")<<endl;
    }
}

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

#define pb(n) push_back(n)
#define fi first
#define se second
#define all(r) (r).begin(),(r).end()
#define gsort(st,en) sort((st),(en),greater<int>())
#define vmax(ary) *max_element(all(ary))
#define vmin(ary) *min_element(all(ary))
#define debug(x) cout<<#x<<": "<<x<<endl
#define fcout(n) cout<<fixed<<setprecision((n))
#define scout(n) cout<<setw(n)
#define vary(type,name,size,init) vector< type> name(size,init)
#define vvl(v,w,h,init) vector<vector<ll>> v(w,vector<ll>(h,init));

#define rep(i,n) for(int i = 0; i < (int)(n);++i)
#define REP(i,a,b) for(int i = (a);i < (int)(b);++i)
#define repi(it,array) for(auto it = array.begin(),end = array.end(); it != end;++it)
#define repa(n,array) for(auto &n :(array))

using ll = long long;
using vi = vector<int>;
using vl = vector<ll>;
using dict = map<string,int>;
using pii = pair<int,int> ;
using pll = pair<ll,ll> ;

const int mod = 1000000007;
constexpr int imax = ((1<<30)-1)*2+1 ;
constexpr int inf = 100000000;
constexpr double PI = acos(-1.0) ;
double eps = 1e-10 ;
const int dy[] = {-1,0,1,0,1,-1,1,-1};
const int dx[] = {0,-1,0,1,1,-1,-1,1};

inline bool value(int x,int y,int w,int h){
  return (x >= 0 && x < w && y >= 0 && y < h);
}
double EPS = 1e-10;
double add(double a, double b){
  if(abs(a+b) < EPS* (abs(a) + abs(b))) return 0;
  return a+b;
}

struct P{
  double x,y;
  P(){}
  P(double _x,double _y):x(_x),y(_y){}
  P operator + (P p){
    return P(add(x,p.x) ,add(y,p.y));
  }
  P operator - (P p){
    return P(add(x,-p.x) ,add(y,-p.y));
  }
  P operator * (double d){
    return P(x * d,y * d);
  }
  friend ostream& operator<<(ostream& os,const P& p){
    os << "("<<p.x <<","<<p.y<<")";
    return os;
  }
  double norm(){
    return sqrt(x*x + y*y);
  }
  double dot(P p){
    return add(x * p.x,y*p.y);
  }
  double det(P p){
    return add(x*p.y,-y*p.x);
  }
  double dist2(P p){
    return ((*this-p).x * (*this-p).x) + ((*this-p).y * (*this-p).y);
  }
  P GetCenter(P &p){
    return P((*this+p).x/2,(*this+p).y/2);
  }
  double GetSlope(P &p){
    P tmp = *this - p;
    return tmp.y/tmp.x;
  }
};
bool on_seg(P p1,P p2,P q){
  return (p1-q).det(p2-q) == 0 && (p1-q).dot(p2-q) <= 0;
}
P intersection(P p1, P p2, P q1,P q2){
  return p1 + (p2-p1) * ((q2 - q1).det(q1-p1) / (q2 - q1).det(p2-p1)) ;
}

int check(P p1,P p2,P p3){
  P a = p2-p1,b = p3 - p1;
  if(a.det(b) > EPS) return 1;
  else if(a.det(b) < -EPS) return -1;
  return 0;
}
bool solve(double a,double b,double c,double d,double e,double f,double xp,double yp){
  P p1 = P(a,b),p2 = P(c,d),p3 = P(e,f),p4 = P(xp,yp);
  int A = check(p1,p2,p4);
  int B = check(p2,p3,p4);
  int C = check(p3,p1,p4);
  if(A == B && B == C && (B == 1 || B == -1)){
    return true;
  }
  return false;
}
int main(){
  cin.tie(0);
  ios::sync_with_stdio(false);
  ll n;
  cin >> n;
  double a,b,c,d,e,f,xk,yk,xs,ys;
  rep(i,n){
    cin >> a >> b >> c >> d >> e >> f >> xk >> yk >> xs >> ys;
    if(solve(a,b,c,d,e,f,xk,yk) == solve(a,b,c,d,e,f,xs,ys)){
      cout << "NG"<<endl;
    }
    else{
      cout << "OK"<<endl;
    }
  }
  return 0;
}