def balayage2(f,k,a,b,n):
    fa,fb=f(a),f(b)
    for i in range(1,n+1):
        h=10**(-i)
        x=a
        if fa<fb:
            while f(x)<k:
                x=x+h
        else:
            while f(x)>k:
                x=x+h
        a=x-h
    return (round(x-h,n),round(x,n))