double height(double mass[], int n){
    double l=0;
    double r;
    r = mass[0];
    while (r-l>0.0000001){
        mass[1]=(l+r)/2;
        bool Up = true;
        for (int i=2; i<n; i++){
            mass[i]=2*mass[i-1]-mass[i-2]+2;
            if (mass[i]<0){
                Up= false;
                break;
            }
        }
        if (Up==true) {
            r = mass[1];
        }
        else {
            l = mass[1];
        }
    }
    return mass[n-1];
}