long long nroot(int n, long long x)
{
    if(x < 0)
        x = -x;
    else if(x == 0)
        return 0;

    long long a = 1, b = x/n+1, m, rez, i;
    while(a <= b)
    {
        m = (a + b) / 2;
        rez = 1;
        for(i = 0; i < n; ++i)
        {
            if(rez*m < rez) // nu permite overflow-ul
                break;
            rez *= m;
        }

        if(i != n || rez > x)
            b = m-1;
        else if(rez == x)
            return m;
        else
            a = m+1;
    }
    return 0;
}