def main():

    from string import ascii_lowercase



    N = int(eval(input()))



    ans = ''

    while N > 0:

        N -= 1

        N, r = divmod(N, 26)

        ans = ascii_lowercase[r] + ans



    print(ans)





if __name__ == '__main__':

    main()



# import sys

# input = sys.stdin.readline

# 

# sys.setrecursionlimit(10 ** 7)

# 

# (int(x)-1 for x in input().split())

# rstrip()

#

# def binary_search(*, ok, ng, func):

#     while abs(ok - ng) > 1:

#         mid = (ok + ng) // 2

#         if func(mid):

#             ok = mid

#         else:

#             ng = mid

#     return ok

def main():

    from string import ascii_lowercase



    N = int(eval(input()))



    def rec(n):

        if n == 0: return ''

        n -= 1

        n, r = divmod(n, 26)

        return rec(n) + ascii_lowercase[r]



    print((rec(N)))





if __name__ == '__main__':

    main()

def main():
    from string import ascii_lowercase

    N = int(eval(input()))
    ans = ""
    while N > 0:
        N -= 1
        N, r = divmod(N, 26)
        ans = ascii_lowercase[r] + ans
    print(ans)


if __name__ == "__main__":
    main()
# import sys
# input = sys.stdin.readline
#
# sys.setrecursionlimit(10 ** 7)
#
# (int(x)-1 for x in input().split())
# rstrip()
#
# def binary_search(*, ok, ng, func):
#     while abs(ok - ng) > 1:
#         mid = (ok + ng) // 2
#         if func(mid):
#             ok = mid
#         else:
#             ng = mid
#     return ok

def main():
    from string import ascii_lowercase

    N = int(eval(input()))

    def rec(n):
        if n == 0:
            return ""
        n -= 1
        n, r = divmod(n, 26)
        return rec(n) + ascii_lowercase[r]

    print((rec(N)))


if __name__ == "__main__":
    main()

-    ans = "" -    while N > 0: -        N -= 1 -        N, r = divmod(N, 26) -        ans = ascii_lowercase[r] + ans -    print(ans) + +    def rec(n): +        if n == 0: +            return "" +        n -= 1 +        n, r = divmod(n, 26) +        return rec(n) + ascii_lowercase[r] + +    print((rec(N))) -# import sys -# input = sys.stdin.readline -# -# sys.setrecursionlimit(10 ** 7) -# -# (int(x)-1 for x in input().split()) -# rstrip() -# -# def binary_search(*, ok, ng, func): -#     while abs(ok - ng) > 1: -#         mid = (ok + ng) // 2 -#         if func(mid): -#             ok = mid -#         else: -#             ng = mid -#     return ok