def balayage(f,k,a,b,n):
    fa,fb=f(a),f(b)
    h=10**(-n)
    x=a
    if fa<fb:
        while f(x)<k:
            x=x+h
    else:
        while f(x)>k:
            x=x+h
    return (round(x-h,n),round(x,n))