package adv2017; import java.io.ByteArrayInputStream; import java.io.IOException; import java.io.InputStream; import java.io.PrintWriter; import java.util.Arrays; import java.util.InputMismatchException; public class N622_2 { InputStream is; PrintWriter out; String INPUT = ""; void solve() { double[][] co = new double[4][]; for(int i = 0;i < 4;i++){ co[i] = new double[3]; for(int j = 0;j < 3;j++){ co[i][j] = nl(); } } for(int i = 1;i < 4;i++){ for(int j = 0;j < 3;j++){ co[i][j] -= co[0][j]; } } double[] N = cross(co[1], co[2]); double[][] M = new double[3][3]; double[] v = new double[3]; for(int i = 0;i < 3;i++){ M[i][0] = co[1][i]; M[i][1] = co[2][i]; M[i][2] = N[i]; v[i] = co[3][i]; } double[] x = solve3x3(M, v); out.println(x[0]+x[1] <= 1 && x[0] >= 0 && x[1] >= 0 ? "YES" : "NO"); } public static double[] solve3x3(double[][] M, double[] V) { double EPS = 1E-10; double det = det3(M); if(Math.abs(det) < EPS)return null; int n = M.length; double[] OM = new double[n]; double[] ret = new double[n]; for(int j = 0;j < n;j++){ for(int i = 0;i < n;i++){ OM[i] = M[j][i]; M[j][i] = V[i]; } ret[j] = det3(M); for(int i = 0;i < n;i++){ M[j][i] = OM[i]; } } return ret; } public static double det3(double[][] M) { return M[0][0]*M[1][1]*M[2][2] -M[0][1]*M[1][0]*M[2][2] -M[0][0]*M[1][2]*M[2][1] -M[0][2]*M[1][1]*M[2][0] +M[1][0]*M[2][1]*M[0][2] +M[0][1]*M[1][2]*M[2][0]; } public static double[] cross(double[] a, double[] b) { return new double[]{ a[1]*b[2]-a[2]*b[1], a[2]*b[0]-a[0]*b[2], a[0]*b[1]-a[1]*b[0] }; } void run() throws Exception { is = INPUT.isEmpty() ? System.in : new ByteArrayInputStream(INPUT.getBytes()); out = new PrintWriter(System.out); long s = System.currentTimeMillis(); solve(); out.flush(); if(!INPUT.isEmpty())tr(System.currentTimeMillis()-s+"ms"); // Thread t = new Thread(null, null, "~", Runtime.getRuntime().maxMemory()){ // @Override // public void run() { // long s = System.currentTimeMillis(); // solve(); // out.flush(); // if(!INPUT.isEmpty())tr(System.currentTimeMillis()-s+"ms"); // } // }; // t.start(); // t.join(); } public static void main(String[] args) throws Exception { new N622_2().run(); } private byte[] inbuf = new byte[1024]; public int lenbuf = 0, ptrbuf = 0; private int readByte() { if(lenbuf == -1)throw new InputMismatchException(); if(ptrbuf >= lenbuf){ ptrbuf = 0; try { lenbuf = is.read(inbuf); } catch (IOException e) { throw new InputMismatchException(); } if(lenbuf <= 0)return -1; } return inbuf[ptrbuf++]; } private boolean isSpaceChar(int c) { return !(c >= 33 && c <= 126); } private int skip() { int b; while((b = readByte()) != -1 && isSpaceChar(b)); return b; } private double nd() { return Double.parseDouble(ns()); } private char nc() { return (char)skip(); } private String ns() { int b = skip(); StringBuilder sb = new StringBuilder(); while(!(isSpaceChar(b))){ // when nextLine, (isSpaceChar(b) && b != ' ') sb.appendCodePoint(b); b = readByte(); } return sb.toString(); } private char[] ns(int n) { char[] buf = new char[n]; int b = skip(), p = 0; while(p < n && !(isSpaceChar(b))){ buf[p++] = (char)b; b = readByte(); } return n == p ? buf : Arrays.copyOf(buf, p); } private int[] na(int n) { int[] a = new int[n]; for(int i = 0;i < n;i++)a[i] = ni(); return a; } private long[] nal(int n) { long[] a = new long[n]; for(int i = 0;i < n;i++)a[i] = nl(); return a; } private char[][] nm(int n, int m) { char[][] map = new char[n][]; for(int i = 0;i < n;i++)map[i] = ns(m); return map; } private int[][] nmi(int n, int m) { int[][] map = new int[n][]; for(int i = 0;i < n;i++)map[i] = na(m); return map; } private int ni() { return (int)nl(); } private long nl() { long num = 0; int b; boolean minus = false; while((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-')); if(b == '-'){ minus = true; b = readByte(); } while(true){ if(b >= '0' && b <= '9'){ num = num * 10 + (b - '0'); }else{ return minus ? -num : num; } b = readByte(); } } private static void tr(Object... o) { System.out.println(Arrays.deepToString(o)); } }