request for any optimizations possible for python solution: not it get TLE #42

import sys

#sys.stdin = open("smalltest.txt")
#sys.stdin = open("input.txt")

top = 0
stack = [0] * 2000020
input = sys.stdin.read().split()
operations = int(input[0])
ans = ""

for i in xrange(operations) :
    op = int(input[i+1])
    if op > 0 :
        stack[top] = op
        top += 1
    elif op < 0 :
        top -= 1
        ans += str(stack[top]) + "\n"
    else :
        if operations - i > top :
            l = max( 0, top - operations + i )
            cnt = top - l
            stack[top:top+cnt] = stack[l:top]
            top += cnt

sys.stdout.write( ans )