Buggy python submission (verdict: Runtime Error):
# coding: utf-8
# Your code here!
import math

N = int(input())

memo = [-1] * int(1e5)
memo[0] = 0
def recursive(n):
    if memo[n] != -1:
        return memo[n]
    
    min_num_operation = int(1e9)
    
    index = int(math.log(n, 9))
    if index > 0:
        min_num_operation = min(min_num_operation, 1 + recursive(int(n - math.pow(9, index))))
        
    index = int(math.log(n, 6))
    if index > 0:
        min_num_operation = min(min_num_operation, 1 + recursive(int(n - math.pow(6, index))))
        
    min_num_operation = min(min_num_operation, n)
    
    memo[n] = min_num_operation
    
    return min_num_operation

print(recursive(N))

Fixed submission:
# coding: utf-8
# Your code here!
import math
from collections import defaultdict
 
N = int(input())
 
memo = defaultdict(lambda: -1)
memo[0] = 0
def recursive(n):
    if memo[n] != -1:
        return memo[n]
    
    min_num_operation = n
    
    index = 0
    temp_n = n
    while temp_n > 0:
        if temp_n % 9 == 0:
            index += 1
            temp_n //= 9
        else:
            index += int(math.log(temp_n, 9))
            break
    if index > 0:
        min_num_operation = min(min_num_operation, 1 + recursive(int(n - math.pow(9, index))))
        
    index = 0
    temp_n = n
    while temp_n > 0:
        if temp_n % 6 == 0:
            index += 1
            temp_n //= 6
        else:
            index += int(math.log(temp_n, 6))
            break
    if index > 0:
        min_num_operation = min(min_num_operation, 1 + recursive(int(n - math.pow(6, index))))
        
    memo[n] = min_num_operation
    
    return min_num_operation
 
print(recursive(N))

Buggy python submission (verdict: Runtime Error):
# coding: utf-8
# Your code here!
import math

N = int(input())

memo = [-1] * int(1e5)
def recursive(n):
    if memo[n] != -1:
        return memo[n]
    
    min_num_operation = int(1e9)
    
    index = int(math.log(n, 9))
    if index > 0:
        min_num_operation = min(min_num_operation, 1 + recursive(int(n - math.pow(9, index))))
        
    index = int(math.log(n, 6))
    if index > 0:
        min_num_operation = min(min_num_operation, 1 + recursive(int(n - math.pow(6, index))))
        
    min_num_operation = min(min_num_operation, n)
    
    memo[n] = min_num_operation
    
    return min_num_operation
    
 
print(recursive(N))

Fixed submission:
# coding: utf-8
# Your code here!
import math
from collections import defaultdict
 
N = int(input())
 
memo = defaultdict(lambda: -1)
memo[0] = 0
def recursive(n):
    if memo[n] != -1:
        return memo[n]
    
    min_num_operation = n
    
    index = 0
    temp_n = n
    while temp_n > 0:
        if temp_n % 9 == 0:
            index += 1
            temp_n //= 9
        else:
            index += int(math.log(temp_n, 9))
            break
    if index > 0:
        min_num_operation = min(min_num_operation, 1 + recursive(int(n - math.pow(9, index))))
        
    index = 0
    temp_n = n
    while temp_n > 0:
        if temp_n % 6 == 0:
            index += 1
            temp_n //= 6
        else:
            index += int(math.log(temp_n, 6))
            break
    if index > 0:
        min_num_operation = min(min_num_operation, 1 + recursive(int(n - math.pow(6, index))))
        
    memo[n] = min_num_operation
    
    return min_num_operation
 
print(recursive(N))