import array as arr
class Stack:
    def __init__(self,size):
        self.stk=arr.array('i',[])
        self.top=-1
        self.size=size
    def spush(self):
        if self.top==self.size:
            print("Stack is full")
        else:
            val=int(input("Enter value to be pushed: "))
            self.stk.append(val)
            self.top+=1
    def spop(self):
        if self.top<0:
            print("Stack is empty")
        else:
            self.stk.pop()
            self.top-=1
    def display(self):
        for i in self.stk:
            print(i,end="  ")
        print("")

s=Stack(4)
while(True):
    print("Choice 1: Push onto stack.")
    print("Choice 2: Pop Stack.")
    print("Choice 3: Display Stack elements.")
    print("Choice 4: Exit.")
    ch=int(input("Enter choice: "))
    if ch==1:
        s.spush()
    elif ch==2:
        s.spop()
    elif ch==3:
        s.display()
    elif ch==4:
        break

# Coded by Saahil