def isBalanced(s):
    history = []
    
    for bracket in s:
        if bracket == '(':
            history.append(')')
        elif bracket == '{':
            history.append('}')
        elif bracket == '[':
            history.append(']')
        else:
            if not history or bracket != history.pop():
                return 'NO'
                
    return 'YES' if not history else 'NO'