def main():

    N = int(eval(input())) - 1

    digits = []



    while True:

        a, b = N // 26, N % 26

        digits.append(b)

        if a == 0:

            break

        N = a - 1



    digits.reverse()

    chars = list(map(to_alphabet, digits))

    print((''.join(chars)))





def to_alphabet(x: int):

    return chr(65 + x).lower()





if __name__ == "__main__":

    main()

def main():

    N = int(eval(input()))

    ans = ''



    while N > 0:

        N -= 1

        ans += chr(ord('a') + N % 26).lower()

        N = N // 26

    print((ans[::-1]))





if __name__ == "__main__":

    main()

def main():
    N = int(eval(input())) - 1
    digits = []
    while True:
        a, b = N // 26, N % 26
        digits.append(b)
        if a == 0:
            break
        N = a - 1
    digits.reverse()
    chars = list(map(to_alphabet, digits))
    print(("".join(chars)))


def to_alphabet(x: int):
    return chr(65 + x).lower()


if __name__ == "__main__":
    main()

def main():
    N = int(eval(input()))
    ans = ""
    while N > 0:
        N -= 1
        ans += chr(ord("a") + N % 26).lower()
        N = N // 26
    print((ans[::-1]))


if __name__ == "__main__":
    main()

-    N = int(eval(input())) - 1 -    digits = [] -    while True: -        a, b = N // 26, N % 26 -        digits.append(b) -        if a == 0: -            break -        N = a - 1 -    digits.reverse() -    chars = list(map(to_alphabet, digits)) -    print(("".join(chars))) - - -def to_alphabet(x: int): -    return chr(65 + x).lower() +    N = int(eval(input())) +    ans = "" +    while N > 0: +        N -= 1 +        ans += chr(ord("a") + N % 26).lower() +        N = N // 26 +    print((ans[::-1]))