#!/usr/bin/env python3

# Calculate area of triangle and compare to areas
# of triangles with one vertex = origin
# better solution -> check sign of cross products

def main():
    tr = parse("data/102_triangles.txt")
    return len([0 for p in tr if areaTR(p) == areaOG(0,2,p) + areaOG(0,4,p) + areaOG(2,4,p)])

def areaTR(p):  #triangle area
    return abs(p[0]*p[3] - p[0]*p[5] + 
               p[2]*p[5] - p[2]*p[1] +
               p[4]*p[1] - p[4]*p[3])

def areaOG(a, b, p): #triangle with with a=0,0
    return abs(p[a]*p[b+1] - p[b]*p[a+1])

def parse(path):
    with open(path) as f:
        return [list(map(int, row.split(","))) for row in f.read()[:-1].split("\n")]

print(main())