def solve(*coefficients):
    if len(coefficients)!=3:raise ValueError
    a,b,c=coefficients
    if a!=0:D=b*b-4*a*c;return[(-b+D**.5)/2/a,(-b-D**.5)/2/a]if D>0 else[-b/2/a]if D==0 else[]
    else:return[-c/b]if b!=0 else[]if c!=0 else['all']