дачники

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
 
double SABC(double AB, double AC, double BC)
{
    double p = (AB + AC + BC) / 2.0;
 
    return sqrt(p * (p - AB) * (p - AC) * (p - BC));
}
 
double PQ(double x1, double y1, double x2, double y2)
{
    return sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2));
}
 
int main()
{
    int N;
    double **arr;
    double S1, S2;
    int count = 0;
    int i, j;
 
    FILE *f;
 
    f = fopen("INPUT.TXT", "r");
    fscanf(f, "%d", &N);
 
    arr = (double **)malloc(N * sizeof(double *));
 
    for (i = 0; i < N; i++)
        arr[i] = (double *)malloc(10 * sizeof(double));
 
    for (i = 0; i < N; i++)
        for (j = 0; j < 10; j++)
            fscanf(f, "%lf", &arr[i][j]);
 
    fclose(f);
 
    for (i = 0; i < N; i++)
    {
        S1 = PQ(arr[i][2], arr[i][3], arr[i][4], arr[i][5]) * PQ(arr[i][2], arr[i][3], arr[i][8], arr[i][9]);
        S2 = SABC(PQ(arr[i][0], arr[i][1], arr[i][2], arr[i][3]), PQ(arr[i][0], arr[i][1], arr[i][4], arr[i][5]), PQ(arr[i][2], arr[i][3], arr[i][4], arr[i][5])) +
             SABC(PQ(arr[i][0], arr[i][1], arr[i][4], arr[i][5]), PQ(arr[i][0], arr[i][1], arr[i][6], arr[i][7]), PQ(arr[i][4], arr[i][5], arr[i][6], arr[i][7])) +
             SABC(PQ(arr[i][0], arr[i][1], arr[i][6], arr[i][7]), PQ(arr[i][0], arr[i][1], arr[i][8], arr[i][9]), PQ(arr[i][6], arr[i][7], arr[i][8], arr[i][9])) +
             SABC(PQ(arr[i][0], arr[i][1], arr[i][8], arr[i][9]), PQ(arr[i][0], arr[i][1], arr[i][2], arr[i][3]), PQ(arr[i][8], arr[i][9], arr[i][2], arr[i][3]));
 
        if (fabs(S1 - S2) < 1E-5)
            count++;
    }
 
    f = fopen("OUTPUT.TXT", "w");
    fprintf(f, "%d", count);
    fclose(f);
 
    for (i = 0; i < N; i++)
        free(arr[i]);
 
    free(arr);
 
    return 0;
}