package adv2019; import java.io.ByteArrayInputStream; import java.io.IOException; import java.io.InputStream; import java.io.PrintWriter; import java.util.Arrays; import java.util.Comparator; import java.util.InputMismatchException; public class D10 { InputStream is; PrintWriter out; String INPUT = "4 -4 -1 -2 -1 2 -3 -5 -1"; void solve() { int n = ni(); int[][] co = new int[n][]; for(int i = 0;i < n;i++) { co[i] = na(2); } int p = 0; for(int i = 0;i < n;i++) { if(co[i][0] == 0 && co[i][1] == 0)continue; co[p++] = co[i]; } co = Arrays.copyOf(co, p); n = p; Arrays.sort(co, compArgi); long ans = (long)n*(n-1)*(n-2)/6; { int k = 0; for(int i = 0;i < n;i++) { while(k-i < n && (isACB(new int[] {0, 0}, co[k%n], co[i]) || ccw(new int[] {0, 0}, co[i], co[k%n]) == -1)) { // tr(co[i], co[k], isACB(co[i], new int[] {0, 0}, co[k])); k++; } ans -= (k-i-1)*(k-i-2)/2; } } tr(ans); for(int i = 0;i < n;) { int same = 1, diff = 0; if(co[i][1] < 0 || co[i][1] == 0 && co[i][0] < 0)break; for(int j = i+1;j < n;j++) { if(ccw(new int[] {0, 0}, co[i], co[j]) == 0) { if(isACB(new int[] {0, 0}, co[j], co[i])) { same++; }else { diff++; } } } // (n-2)+(n-3)+..+(n-diff-1) // (n-3)+(n-4)+..+(n-diff-2) // (n-same-1)+... long s = 0; for(int k = 2;k <= diff+1;k++) { s += n-k; } for(int k = 2;k <= same+1;k++) { ans -= s; s -= diff; } i += same; } out.println(ans); } public static boolean isACB(long ax, long ay, long bx, long by, long cx, long cy) { return (cx-ax)*(by-ay)-(cy-ay)*(bx-ax)==0 && (cx-ax)*(cx-bx)+(cy-ay)*(cy-by) <= 0; } public static boolean isACB(long[] a, long[] b, long[] c) { return isACB(a[0], a[1], b[0], b[1], c[0], c[1]); } public static boolean isACB(int[] a, int[] b, int[] c) { return isACB(a[0], a[1], b[0], b[1], c[0], c[1]); } public static int ccw(long ax, long ay, long bx, long by, long tx, long ty){ return Long.signum((tx-ax)*(by-ay)-(bx-ax)*(ty-ay)); } public static int ccw(long[] a, long[] b, long[] t){ return Long.signum((t[0]-a[0])*(b[1]-a[1])-(b[0]-a[0])*(t[1]-a[1])); } public static int ccw(int[] a, int[] b, int[] t){ return Long.signum((long)(t[0]-a[0])*(b[1]-a[1])-(long)(b[0]-a[0])*(t[1]-a[1])); } public static Comparator compArgi = new Comparator(){ public int compare(int[] a, int[] b) { long ax = a[0], ay = a[1]; long bx = b[0], by = b[1]; int za = ay > 0 || ay == 0 && ax > 0 ? 0 : 1; int zb = by > 0 || by == 0 && bx > 0 ? 0 : 1; if(za != zb)return za - zb; if(ay*bx-ax*by != 0)return Long.signum(ay*bx-ax*by); return Long.signum((ax*ax+ay*ay)-(bx*bx+by*by)); } }; 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 D10().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)); } }