import sys

INF = 1 << 60

MOD = 10**9 + 7 # 998244353

sys.setrecursionlimit(2147483647)

input = lambda:sys.stdin.readline().rstrip()

def resolve():

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

    res = []

    while 1:

        res.append(chr(ord('a') + n % 26))

        n = n // 26 - 1

        if n == -1:

            break



    res.reverse()

    print((''.join(res)))

resolve()
n = int(eval(input()))

ans = []

while n:

  n, r = divmod(n - 1, 26)

  ans.append(chr(ord('a') + r))

ans.reverse()

print((''.join(ans)))

import sys

INF = 1 << 60
MOD = 10**9 + 7  # 998244353
sys.setrecursionlimit(2147483647)
input = lambda: sys.stdin.readline().rstrip()


def resolve():
    n = int(eval(input())) - 1
    res = []
    while 1:
        res.append(chr(ord("a") + n % 26))
        n = n // 26 - 1
        if n == -1:
            break
    res.reverse()
    print(("".join(res)))


resolve()

n = int(eval(input()))
ans = []
while n:
    n, r = divmod(n - 1, 26)
    ans.append(chr(ord("a") + r))
ans.reverse()
print(("".join(ans)))

-import sys - -INF = 1 << 60 -MOD = 10**9 + 7  # 998244353 -sys.setrecursionlimit(2147483647) -input = lambda: sys.stdin.readline().rstrip() - - -def resolve(): -    n = int(eval(input())) - 1 -    res = [] -    while 1: -        res.append(chr(ord("a") + n % 26)) -        n = n // 26 - 1 -        if n == -1: -            break -    res.reverse() -    print(("".join(res))) - - -resolve() +n = int(eval(input())) +ans = [] +while n: +    n, r = divmod(n - 1, 26) +    ans.append(chr(ord("a") + r)) +ans.reverse() +print(("".join(ans)))