Подсчитать количество точек множества, находящихся внутри этого треугольника - QBasic

DEFSNG E, R-S, X-Y
DEFINT F, I-K
OPTION BASE 1
e = .00001
 
DEF FNF (x1, y1, x2, y2, x3, y3)
  FNF = ABS((x2 - x1) * (y3 - y1) - (x3 - x1) * (y2 - y1)) / 2
END DEF
 
 
DEF FNN (x1, y1, x2, y2, x3, y3, x4, y4)
   FNN = 0
   s1 = FNF(x1, y1, x2, y2, x4, y4)
   s2 = FNF(x1, y1, x3, y3, x4, y4)
   s3 = FNF(x2, y2, x3, y3, x4, y4)
   s4 = FNF(x1, y1, x2, y2, x3, y3)
   IF ABS(s1 + s2 + s3 - s4) < e THEN FNN = 1
END DEF
 
RANDOMIZE TIMER
CLS
INPUT "Vvedite N"; n
DIM x(n)
DIM y(n)
 
FOR i = 1 TO n
   x(i) = 10 * RND
   y(i) = 10 * RND
NEXT i
 
r0 = 0
x1 = x(1)
y1 = y(1)
x2 = x(2)
y2 = y(2)
 
FOR i = 1 TO n - 1
   FOR j = i + 1 TO n
      r = SQR((x(i) - x(j)) ^ 2 + (y(i) - y(j)) ^ 2)
      IF r0 < r THEN
         r0 = r
         x1 = x(i)
         y1 = y(i)
         x2 = x(j)
         y2 = y(j)
      END IF
   NEXT j
NEXT i
 
k = 0
FOR i = 1 TO n
   k = k + FNN(x1, y1, x2, y2, 10, 0, x(i), y(i))
NEXT i
 
SCREEN 12
WINDOW SCREEN (-1, -1)-(11, 11)
LINE (0, 0)-(10, 10), 13, B
 
FOR i = 1 TO n
 PSET (x(i), y(i)), 15
NEXT i
 
LINE (x1, y1)-(x2, y2), 11
LINE (x1, y1)-(10, 0), 11
LINE (x2, y2)-(10, 0), 11
PRINT "KOLICHESTVO TOCHEK ="; k - 2
END