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#include <bits/stdc++.h>
using namespace std;
#define FOR(i, j, k) for(int i = j; i < k; ++i)
#define rep(i, j) FOR(i, 0, j)
#define repr(i, j) for(int i = j; i >= 0; --i)
#define INF (1 << 30)
#define MOD 1e9 + 7
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> P;
struct Vector { double x; double y; };
Vector sub_vector(const Vector& a, const Vector& b) {
Vector ret;
ret.x = a.x - b.x;
ret.y = a.y - b.y;
return ret;
}
int main() {
double x1, y1, x2, y2, x3, y3, px, py;
while(cin >> x1 >> y1 >> x2 >> y2 >> x3 >> y3 >> px >> py) {
Vector A, B, C, P;
A.x = x1; A.y = y1;
B.x = x2; B.y = y2;
C.x = x3; C.y = y3;
P.x = px; P.y = py;
Vector AB = sub_vector(B, A);
Vector BP = sub_vector(P, B);
Vector BC = sub_vector(C, B);
Vector CP = sub_vector(P, C);
Vector CA = sub_vector(A, C);
Vector AP = sub_vector(P, A);
double c1 = AB.x * BP.y - AB.y * BP.x;
double c2 = BC.x * CP.y - BC.y * CP.x;
double c3 = CA.x * AP.y - CA.y * AP.x;
if((c1 > 0 && c2 > 0 && c3 > 0) || (c1 < 0 && c2 < 0 && c3 < 0)) printf("YES\n");
else printf("NO\n");
}
return 0;
}
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