Buggy python submission (verdict: Runtime Error):
import string

# 1千兆 + 1
N = int(input())
n_digits = len(str(1000000000000001))
letters = string.ascii_lowercase

x = N
ans = []
# while True:
#     x -= 1
#     mod = x % 26
#     ans = [ mod ] + ans
#     x = x // 26
#     if x <= 0:
#         break

# print(ans)
# print("".join([ letters[v] for v in ans ]))

while True:
    x -= 1
    mod = x % 26
    # div = x // 26
    x = x // 26
    
    ans.append(mod)
    if div == 0:
        break

ans = ans[::-1]
print("".join([ letters[v] for v in ans ]))

Fixed submission:
import string

# 1千兆 + 1
N = int(input())
n_digits = len(str(1000000000000001))
letters = string.ascii_lowercase

x = N - 1
ans = []
# while True:
#     mod = x % 26
#     ans = [ mod ] + ans
#     x = x // 26
#     if x <= 0:
#         if ans[0] == 0:
#             ans = [0] + ans
#         break

# print(ans)
# print("".join([ letters[v] for v in ans ]))

while True:
    mod = x % 26
    div = x // 26
    
    ans.append(mod)
    if div == 0:
        break
    x = div - 1

ans = ans[::-1]
# print(ans)
print("".join([ letters[v] for v in ans ]))

Buggy python submission (verdict: Runtime Error):
import string

# 1千兆 + 1
N = int(input())
n_digits = len(str(1000000000000001))
letters = string.ascii_lowercase

x = N - 1
ans = []
# while True:
#     x -= 1
#     mod = x % 26
#     ans = [ mod ] + ans
#     x = x // 26
#     if x <= 0:
#         break

# print(ans)
# print("".join([ letters[v] for v in ans ]))

while True:
    x -= 1
    mod = x % 26
    # div = x // 26
    x = x // 26
    
    ans.append(mod)
    if div == 0:
        break

ans = ans[::-1]
print("".join([ letters[v] for v in ans ]))

Fixed submission:
import string

# 1千兆 + 1
N = int(input())
n_digits = len(str(1000000000000001))
letters = string.ascii_lowercase

x = N - 1
ans = []
# while True:
#     mod = x % 26
#     ans = [ mod ] + ans
#     x = x // 26
#     if x <= 0:
#         if ans[0] == 0:
#             ans = [0] + ans
#         break

# print(ans)
# print("".join([ letters[v] for v in ans ]))

while True:
    mod = x % 26
    div = x // 26
    
    ans.append(mod)
    if div == 0:
        break
    x = div - 1

ans = ans[::-1]
# print(ans)
print("".join([ letters[v] for v in ans ]))

Buggy python submission (verdict: Runtime Error):
import string

# 1千兆 + 1
N = int(input())
n_digits = len(str(1000000000000001))
map_letters = { i:v for i,v in enumerate(string.ascii_lowercase)}

x = N - 1
ans = []
for d in range(n_digits):
    if x == 0:
        break
    mod = x % 26
    ans = [ mod ] + ans
    x = x // 26

fa = []
for i in range(len(ans)-1):
    fa.append(ans[i]-1)
fa.append(ans[-1])
print(
    ''.join(map(lambda d: map_letters[d], fa))
)

Fixed submission:
import string

# 1千兆 + 1
N = int(input())
n_digits = len(str(1000000000000001))
letters = string.ascii_lowercase

x = N - 1
ans = []
# while True:
#     mod = x % 26
#     ans = [ mod ] + ans
#     x = x // 26
#     if x <= 0:
#         if ans[0] == 0:
#             ans = [0] + ans
#         break

# print(ans)
# print("".join([ letters[v] for v in ans ]))

while True:
    mod = x % 26
    div = x // 26
    
    ans.append(mod)
    if div == 0:
        break
    x = div - 1

ans = ans[::-1]
# print(ans)
print("".join([ letters[v] for v in ans ]))

Buggy python submission (verdict: Runtime Error):
import string

# 1千兆 + 1
N = int(input())
n_digits = len(str(1000000000000001))
map_letters = { i+1:v for i,v in enumerate(string.ascii_lowercase)}

x = N
ans = []
for d in range(n_digits):
    if x == 0:
        break
    mod = x % 26
    ans = [ mod ] + ans
    x = x // 26

print(
    ''.join(map(lambda d: map_letters[d], ans))
)

Fixed submission:
import string

# 1千兆 + 1
N = int(input())
n_digits = len(str(1000000000000001))
letters = string.ascii_lowercase

x = N - 1
ans = []
# while True:
#     mod = x % 26
#     ans = [ mod ] + ans
#     x = x // 26
#     if x <= 0:
#         if ans[0] == 0:
#             ans = [0] + ans
#         break

# print(ans)
# print("".join([ letters[v] for v in ans ]))

while True:
    mod = x % 26
    div = x // 26
    
    ans.append(mod)
    if div == 0:
        break
    x = div - 1

ans = ans[::-1]
# print(ans)
print("".join([ letters[v] for v in ans ]))