from bisect import *
from math import *
import sys

sys.setrecursionlimit(10 ** 6)
int1 = lambda x: int(x) - 1
p2D = lambda x: print(*x, sep="\n")
def MI(): return map(int, sys.stdin.readline().split())
def LI(): return list(map(int, sys.stdin.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]

def main():
    n = int(input())
    rad = []
    rxy = []
    for _ in range(n):
        x, y = MI()
        rxy.append((atan2(y, x), x, y))
    rxy.sort()
    rad = [r for r, x, y in rxy]
    # print(rxy)
    # print(rad)
    ans = 0
    for i, (r0, x0, y0) in enumerate(rxy[:-2]):
        if r0 >= 0: break
        r0p = atan2(-y0, -x0)
        L = bisect_right(rad, r0p)
        for r1, x1, y1 in rxy[i + 1:]:
            if r0 == r1: continue
            if r1 >= r0p: break
            r1p = atan2(-y1, -x1)
            R = bisect_left(rad, r1p)
            if r1p < 0: R = n
            ans += R - L
            # print(i, r0, x0, y0, atan2(-y0, -x0), L)
            # print(r1, x1, y1, atan2(-y1, -x1), R)
    print(ans)

main()