def checkio(expression):
    OPENING_BRACKETS = ["(", "[", "{"]
    CLOSING_BRACKETS = [")", "]", "}"]
    current_bracket = []
    for letter in expression:
        if letter in CLOSING_BRACKETS:
            if len(current_bracket) == 0:
                return False
            else:
                last_bracket = current_bracket[-1:][0]
                if OPENING_BRACKETS.index(last_bracket) == CLOSING_BRACKETS.index(letter):
                    current_bracket.pop()
                else:
                    return False
        if letter in OPENING_BRACKETS:
            current_bracket.append(letter)
    return len(current_bracket) == 0


# These "asserts" using only for self-checking and not necessary for auto-testing
if __name__ == '__main__':
    assert checkio("((5+3)*2+1)") == True, "Simple"
    assert checkio("{[(3+1)+2]+}") == True, "Different types"
    assert checkio("(3+{1-1)}") == False, ") is alone inside {}"
    assert checkio("[1+1]+(2*2)-{3/3}") == True, "Different operators"
    assert checkio("(({[(((1)-2)+3)-3]/3}-3)") == False, "One is redundant"
    assert checkio("2+3") == True, "No brackets, no problem"
    assert checkio("(((([[[{{{3}}}]]]]))))") == False, "No brackets, no problem"