Palindrome

import sys
def longestPalSubstr(string):
    maxLength = 1
 
    start = 0
    length = len(string)
 
    low = 0
    high = 0
    for i in xrange(1, length):
        low = i - 1
        high = i
        while low >= 0 and high < length and string[low] == string[high]:
            if high - low + 1 > maxLength:
                start = low
                maxLength = high - low + 1
            low -= 1
            high += 1
        low = i - 1
        high = i + 1
        while low >= 0 and high < length and string[low] == string[high]:
            if high - low + 1 > maxLength:
                start = low
                maxLength = high - low + 1
            low -= 1
            high += 1
 
    print string[start:start + maxLength]
 
    return maxLength
s = sys.stdin.readline()
longestPalSubstr(s)

Test 1

Verdict: TIME LIMIT EXCEEDED

Test 2

Verdict: TIME LIMIT EXCEEDED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: TIME LIMIT EXCEEDED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: TIME LIMIT EXCEEDED