#include <stdio.h>
int num(const char *name, int *res);
int num(const char *name, int *res)
{
    FILE*fp; double x2, x1; int count = 0, countg = 0, counta = 0, counte = 0, opr = 0;
    double arifm, geom;
    if (!(fp = fopen(name, "r")))
        return -1;
    fscanf(fp, "%lf", &x1);
    if (feof(fp))
    {
        fclose(fp);
        *res = 4;
        return 0;
    }
    fscanf(fp, "%lf", &x2);
    if (feof(fp))
    {
        fclose(fp);
        if (x2>x1 || x2<x1) *res = 4;
        else *res = 3;
        return 0;
    }
    arifm = x2 - x1;
    if ((x2<0 || x2>0) && (x1<0 || x1>0)) geom = x2 / x1;
    x1 = x2;

        while (fscanf(fp, "%lf", &x2) == 1)
        {

            count++;
           if ((x2<0 || x2>0) && (x1<0 || x1>0))
           {
            if ((x2 > x1 || x2 < x1))
            {

                  if (x2 / x1 <= geom && x2 / x1 >= geom) countg++;
                if (x2 - x1 <= arifm && x2 - x1 >= arifm) counta++;
                if (countg > 0 && counta > 0 && (x2 - x1<x2 / x1 || x2 - x1>x2 / x1))
                {
                    if (countg == 1) countg = 0;
                    else counta = 0;
                    fclose(fp);
                    *res = 0;
                    return 0;
                }

            }
            else counte++;
           }
           else {if (x2>=x1  && x2<x1)counte++; }

            x1 = x2;
        }
        if (count == counta) opr = 1;
        if (count == countg) opr = 2;
        if (count == counte) opr = 3;

    if (!feof(fp))
    {
        fclose(fp);
        return -2;
    }
    fclose(fp);
    *res = opr;
    return 0;

}
int main(void)
{
    const char *fname = "a.txt";
    int answer; int ret;
    ret = num(fname, &answer);
    if (ret < 0)
    {
        switch (ret)
        {
        case -1:
            printf("Cannot open %s\n", fname);
            break;
        case -2:
            printf("Cannot read %s\n", fname);
            break;
        default:
            printf("Error %d in file %s\n", ret, fname);

        }
        return 1;
    }
    printf("posl = %d\n", answer);
    return 0;
}