#include using namespace std; typedef long long ll; typedef vector vi; typedef vector vl; typedef pair pii; typedef pair pll; typedef int _loop_int; #define REP(i,n) for(_loop_int i=0;i<(_loop_int)(n);++i) #define FOR(i,a,b) for(_loop_int i=(_loop_int)(a);i<(_loop_int)(b);++i) #define FORR(i,a,b) for(_loop_int i=(_loop_int)(b)-1;i>=(_loop_int)(a);--i) #define DEBUG(x) cout<<#x<<": "< P; Real x[4], y[4], z[4]; P ps[4]; int ccw(P a, P b, P c){ b -= a; c -= a; return imag(conj(b)*c) < 0.0; } int main(){ REP(i,4)cin>>x[i]>>y[i]>>z[i]; // origin point(2) REP(i,4)if(i!=2){ x[i]-=x[2]; y[i]-=y[2]; z[i]-=z[2]; } x[2] = y[2] = z[2] = 0.0; // (xy) rotate point(1) - origin { P rot = P(x[1], y[1]); rot /= abs(rot); REP(i,4){ P p = P(x[i], y[i]) / rot; x[i] = real(p); y[i] = imag(p); } } // y[1] == 0 // (xz) rotate point(1) - origin { P rot = P(x[1], z[1]); rot /= abs(rot); REP(i,4){ P p = P(x[i], z[i]) / rot; x[i] = real(p); z[i] = imag(p); } } // z[1] == 0 // (yz) rotate point(0) - origin { P rot = P(y[0], z[0]); rot /= abs(rot); REP(i,4){ P p = P(y[i], z[i]) / rot; y[i] = real(p); z[i] = imag(p); } } // ok REP(i,4)ps[i] = P(x[i], y[i]); int xs = 0; REP(i,3)xs += ccw(ps[i], ps[(i+1)%3], ps[3]); if(xs==0 || xs==3){ puts("YES"); }else{ puts("NO"); } return 0; }