def main():

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

    digits = []



    while True:

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

        if a == 0:

            digits.append(b)

            break

        digits.append(b)

        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())) - 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())) - 1
    digits = []
    while True:
        a, b = N // 26, N % 26
        if a == 0:
            digits.append(b)
            break
        digits.append(b)
        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())) - 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()

+        digits.append(b) -            digits.append(b) -        digits.append(b)