void insertion_sort2(Student *tab, int n){
    Student pom;
    int j;
    for (int i = 1; i<n; i++){
        if (tab[i].month<=tab[i-1].month){
            if (tab[i].month<tab[i-1].month){
                pom=tab[i];
                for (j=i-1; (j>=0)&& tab[j].month>pom.month; j--)
                    tab[j+1]=tab[j];
                tab[j+1] = pom;
            }
            else if (tab[i].month == tab[i-1].month){
                if (tab[i].grades<tab[i-1].grades){
                    pom=tab[i];
                    for (j=i-1; (j>=0)&& tab[j].grades>pom.grades; j--)
                        tab[j+1]=tab[j];
                    tab[j+1] = pom;
                }
                else if (tab[i].grades==tab[i-1].grades){
                    if (tab[i].meters<tab[i-1].meters){
                        pom=tab[i];
                        for (j=i-1; (j>=0)&& tab[j].meters>pom.meters; j--)
                            tab[j+1]=tab[j];
                        tab[j+1] = pom;
                    }
                    else if (tab[i].meters==tab[i-1].meters){
                        if (tab[i].number>tab[i-1].number){
                            pom=tab[i];
                            for (j=i-1; (j>=0)&& tab[j].number>pom.number; j--)
                                tab[j+1]=tab[j];
                            tab[j+1] = pom;
                        }
                    }
                }
            }
        }
    }
}