#https://leetcode.com/problems/min-stack/

class MinStack(object):

def __init__(self):

self.stack = []

def push(self, x):

self.stack.append((x, min(x, self.getMin())))

def pop(self):

if len(self.stack)==0: return None

return self.stack.pop()[0]

def top(self):

if len(self.stack)==0: return None

return self.stack[-1][0]

def getMin(self):

if len(self.stack)==0: return float('inf')

return self.stack[-1][1]

# Your MinStack object will be instantiated and called as such:

# obj = MinStack()

# obj.push(x)

# obj.pop()

# param_3 = obj.top()

# param_4 = obj.getMin()