class PreconditionError(Exception):
    pass

class ComplexRootError(Exception):
    pass

def solve(a, b, c):
    if not ((isinstance(a, float) or isinstance(a, int)) and (isinstance(b, float) or isinstance(b, int)) and (isinstance(c, float) or isinstance(c, int))):
        raise TypeError
    if a == 0:
        raise PreconditionError
    if b*b - 4*a*c < 0:
        raise ComplexRootError
    d = float((b*b - 4*a*c)**0.5)
    res = (-b - d) / (a * 2), (-b + d) / (a * 2)
    if res[0] == res[1]:
        return (res[0])
    else:
        return res