def main():

    n = int(eval(input()))

    base = 26

    orig = ord('a')

    ans = ''

    for exp in range(1, 12):

        if (tmp := pow(base, exp)) >= n:

            n -= 1  # zero_indexed for ASCII mod

            for digit in range(exp):

                ans += (chr(orig + n % base))

                n //= base

            break

        else:

            n -= tmp

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





if __name__ == '__main__':

    main()

def main():

    n = int(eval(input()))

    base = 26

    orig = ord('a')

    ans = ''

    while n > 0:

        n -= 1

        ans += chr(orig + n % base)

        n //= base

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





if __name__ == '__main__':

    main()

def main():
    n = int(eval(input()))
    base = 26
    orig = ord("a")
    ans = ""
    for exp in range(1, 12):
        if (tmp := pow(base, exp)) >= n:
            n -= 1  # zero_indexed for ASCII mod
            for digit in range(exp):
                ans += chr(orig + n % base)
                n //= base
            break
        else:
            n -= tmp
    print((ans[::-1]))


if __name__ == "__main__":
    main()

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


if __name__ == "__main__":
    main()

-    for exp in range(1, 12): -        if (tmp := pow(base, exp)) >= n: -            n -= 1  # zero_indexed for ASCII mod -            for digit in range(exp): -                ans += chr(orig + n % base) -                n //= base -            break -        else: -            n -= tmp +    while n > 0: +        n -= 1 +        ans += chr(orig + n % base) +        n //= base