Buggy python submission (verdict: Runtime Error):
#!/usr/bin/env python3
import sys
import string

l = [None]+[c for c in string.ascii_lowercase]
def f(N: int):
    N -= 1
    if N // 26:
        return f(N//26) + l[N%26]
    else:
        return l[N%26]

def solve(N):
    print(f(N))

# Generated by 1.1.7.1 https://github.com/kyuridenamida/atcoder-tools  (tips: You use the default template now. You can remove this line by using your custom template)
def main():
    def iterate_tokens():
        for line in sys.stdin:
            for word in line.split():
                yield word
    tokens = iterate_tokens()
    N = int(next(tokens))  # type: int
    solve(N)

if __name__ == '__main__':
    main()


Fixed submission:
#!/usr/bin/env python3
import sys
import string

l = [c for c in string.ascii_lowercase]
def f(N: int):
    N -= 1
    if N // 26:
        return f(N//26) + l[N%26]
    else:
        return l[N%26]

def solve(N):
    print(f(N))

# Generated by 1.1.7.1 https://github.com/kyuridenamida/atcoder-tools  (tips: You use the default template now. You can remove this line by using your custom template)
def main():
    def iterate_tokens():
        for line in sys.stdin:
            for word in line.split():
                yield word
    tokens = iterate_tokens()
    N = int(next(tokens))  # type: int
    solve(N)

if __name__ == '__main__':
    main()

Buggy python submission (verdict: Runtime Error):
#!/usr/bin/env python3
import sys
import string

l = [None]+[c for c in string.ascii_lowercase]
def f(N: int):
    if N // 26:
        return f(N//26) + l[N%26]
    else:
        return l[N%26]

def solve(N):
    print(f(N))

# Generated by 1.1.7.1 https://github.com/kyuridenamida/atcoder-tools  (tips: You use the default template now. You can remove this line by using your custom template)
def main():
    def iterate_tokens():
        for line in sys.stdin:
            for word in line.split():
                yield word
    tokens = iterate_tokens()
    N = int(next(tokens))  # type: int
    solve(N)

if __name__ == '__main__':
    main()


Fixed submission:
#!/usr/bin/env python3
import sys
import string

l = [c for c in string.ascii_lowercase]
def f(N: int):
    N -= 1
    if N // 26:
        return f(N//26) + l[N%26]
    else:
        return l[N%26]

def solve(N):
    print(f(N))

# Generated by 1.1.7.1 https://github.com/kyuridenamida/atcoder-tools  (tips: You use the default template now. You can remove this line by using your custom template)
def main():
    def iterate_tokens():
        for line in sys.stdin:
            for word in line.split():
                yield word
    tokens = iterate_tokens()
    N = int(next(tokens))  # type: int
    solve(N)

if __name__ == '__main__':
    main()

Buggy python submission (verdict: Runtime Error):
#!/usr/bin/env python3
import sys
import string

l = [None]+[c for c in string.ascii_lowercase]
def f(N: int):
    if N // 26:
        return f(N//26) + l[N%26]
    else:
        return l[N%26]

def solve(N):
    print(f(N))

# Generated by 1.1.7.1 https://github.com/kyuridenamida/atcoder-tools  (tips: You use the default template now. You can remove this line by using your custom template)
def main():
    def iterate_tokens():
        for line in sys.stdin:
            for word in line.split():
                yield word
    tokens = iterate_tokens()
    N = int(next(tokens))  # type: int
    solve(N)

if __name__ == '__main__':
    main()


Fixed submission:
#!/usr/bin/env python3
import sys
import string

l = [c for c in string.ascii_lowercase]
def f(N: int):
    N -= 1
    if N // 26:
        return f(N//26) + l[N%26]
    else:
        return l[N%26]

def solve(N):
    print(f(N))

# Generated by 1.1.7.1 https://github.com/kyuridenamida/atcoder-tools  (tips: You use the default template now. You can remove this line by using your custom template)
def main():
    def iterate_tokens():
        for line in sys.stdin:
            for word in line.split():
                yield word
    tokens = iterate_tokens()
    N = int(next(tokens))  # type: int
    solve(N)

if __name__ == '__main__':
    main()