CBS

stack = []
is_error = False
for bracket in input():
    if bracket == '(':
        stack.append(')')
    elif bracket == '[':
        stack.append(']')
    elif bracket == '{':
        stack.append('}')
    else:
        if len(stack) == 0 or stack[-1] != bracket:
            is_error = True
            break
        stack.pop()
print("yes" if len(stack) == 0 and not is_error else "no")