Python 3:

Write your code here

stack = []
pairs = {
    '[': ']',
    '{': '}',
    '(': ')'
}

for bracket in s:
    if bracket in pairs:
        stack.append(bracket)
    elif not stack or pairs.get(stack.pop(-1)) != bracket:
        return 'NO'

return 'YES' if not stack else 'NO'