def solve():
palin = 0
for i in range(start, end):
for j in range(i, end):
a = i * j
if a >= palin and palindrome(str(a)):
palin = a
return palin
def solve_3():
palin = 0
for i in range(end, start - 1, -1):
for j in range(end, i - 1, -1):
a = i * j
if a < palin:
break
if palindrome(str(a)):
palin = a
return palin
def solve_4():
return max(filter(lambda x: palindrome(str(x)), (a * b for a in range(start, end + 1) for b in range(a, end + 1))))