import std.conv, std.functional, std.range, std.stdio, std.string;
import std.algorithm, std.array, std.bigint, std.complex, std.container, std.math, std.numeric, std.regex, std.typecons;
import core.bitop;

class EOFException : Throwable { this() { super("EOF"); } }
string[] tokens;
string readToken() { for (; tokens.empty; ) { if (stdin.eof) { throw new EOFException; } tokens = readln.split; } auto token = tokens.front; tokens.popFront; return token; }
int readInt() { return readToken.to!int; }
long readLong() { return readToken.to!long; }
real readReal() { return readToken.to!real; }

bool chmin(T)(ref T t, in T f) { if (t > f) { t = f; return true; } else { return false; } }
bool chmax(T)(ref T t, in T f) { if (t < f) { t = f; return true; } else { return false; } }

int binarySearch(alias pred, T)(in T[] as) { int lo = -1, hi = cast(int)(as.length); for (; lo + 1 < hi; ) { const mid = (lo + hi) >> 1; (unaryFun!pred(as[mid]) ? hi : lo) = mid; } return hi; }
int lowerBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a >= val)); }
int upperBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a > val)); }


alias Pt = Tuple!(long, "x", long, "y");
int sig(long r) {
  return (r > 0) ? +1 : (r < 0) ? -1 : 0;
}
long tri(Pt a, Pt b, Pt c) {
  return (b.x - a.x) * (c.y - a.y) - (b.y - a.y) * (c.x - a.x);
}
Pt[] convexHull(Pt[] ps) {
  auto qs = new Pt[ps.length + 1];
  ps.sort!((a, b) => (a.x < b.x));
  int m = 0;
  foreach (p; ps) {
    for (; m > 1 && sig(tri(qs[m - 2], qs[m - 1], p)) <= 0; --m) {}
    qs[m++] = p;
  }
  const r = m;
  foreach_reverse (p; ps) {
    for (; m > r && sig(tri(qs[m - 2], qs[m - 1], p)) <= 0; --m) {}
    qs[m++] = p;
  }
  return qs[0 .. m - 1];
}


enum N = 5;

Pt[] P;

void main() {
  try {
    for (; ; ) {
      P = new Pt[N];
      foreach (i; 0 .. N) {
        P[i].x = readLong();
        P[i].y = readLong();
      }
      
      const qs = convexHull(P);
      debug {
        writeln(qs);
      }
      writeln((qs.length == 5) ? "YES" : "NO");
    }
  } catch (EOFException e) {
  }
}