def base_k(n, k=26):

    ret = []

    ny = n

    while ny:



        ret.append(ny % k)

        ny //= k

    return ret[::-1]





def letter(i):

    return chr(i+97)





def solve(n):

    check = 26

    cnt = 1

    k = n

    while True:

        if n <= check:

            break

        check *= 26

        check += 26

        cnt += 1

    k -= check//26 - 1

    t = base_k(k-1)

    ans = ""

    if not t:

        ans = "a" * cnt

    else:

        for _ in range(cnt):

            if not t:

                ans += "a"

                continue

            ans += letter(t.pop())



    return ans[::-1]





n = int(eval(input()))

print((solve(n)))

def answer(n):

    if n <= 26:

        return chr(n-1 + 97)

    r = n % 26 - 1

    if r == -1:

        r += 26

    return answer((n-r) // 26) + chr(r + 97)





n = int(eval(input()))

print((answer(n)))
def base_k(n, k=26):
    ret = []
    ny = n
    while ny:
        ret.append(ny % k)
        ny //= k
    return ret[::-1]


def letter(i):
    return chr(i + 97)


def solve(n):
    check = 26
    cnt = 1
    k = n
    while True:
        if n <= check:
            break
        check *= 26
        check += 26
        cnt += 1
    k -= check // 26 - 1
    t = base_k(k - 1)
    ans = ""
    if not t:
        ans = "a" * cnt
    else:
        for _ in range(cnt):
            if not t:
                ans += "a"
                continue
            ans += letter(t.pop())
    return ans[::-1]


n = int(eval(input()))
print((solve(n)))

def answer(n):
    if n <= 26:
        return chr(n - 1 + 97)
    r = n % 26 - 1
    if r == -1:
        r += 26
    return answer((n - r) // 26) + chr(r + 97)


n = int(eval(input()))
print((answer(n)))

-def base_k(n, k=26): -    ret = [] -    ny = n -    while ny: -        ret.append(ny % k) -        ny //= k -    return ret[::-1] - - -def letter(i): -    return chr(i + 97) - - -def solve(n): -    check = 26 -    cnt = 1 -    k = n -    while True: -        if n <= check: -            break -        check *= 26 -        check += 26 -        cnt += 1 -    k -= check // 26 - 1 -    t = base_k(k - 1) -    ans = "" -    if not t: -        ans = "a" * cnt -    else: -        for _ in range(cnt): -            if not t: -                ans += "a" -                continue -            ans += letter(t.pop()) -    return ans[::-1] +def answer(n): +    if n <= 26: +        return chr(n - 1 + 97) +    r = n % 26 - 1 +    if r == -1: +        r += 26 +    return answer((n - r) // 26) + chr(r + 97) -print((solve(n))) +print((answer(n)))