def to_n(x,n):

    ans=[]

    if x==0:

        return [0]

    while x>0:

        x-=1

        ans.append(x%n)

        x//=n

    return ans[::-1]



from sys import stdin

def main():

    #入力

    readline=stdin.readline

    n=int(readline())



    alp=[chr(i) for i in range(97,97+26)]

    m=to_n(n,26)

    ans=[alp[m[i]] for i in range(len(m))]

    print(("".join(ans)))



if __name__=="__main__":

    main()
def to_n(x,n,cnt):

    ans=[]

    for _ in range(cnt):

        ans.append(x%n)

        x//=n

    return ans[::-1]



from sys import stdin

def main():

    #入力

    readline=stdin.readline

    n=int(readline())



    alp=[chr(i) for i in range(97,97+26)]



    tmp=26

    cnt=1

    while n>tmp:

        n-=tmp

        tmp*=26

        cnt+=1

    

    n-=1

    m=to_n(n,26,cnt)

    ans="".join([alp[m[i]] for i in range(len(m))])

    print(ans)



if __name__=="__main__":

    main()
def to_n(x, n):
    ans = []
    if x == 0:
        return [0]
    while x > 0:
        x -= 1
        ans.append(x % n)
        x //= n
    return ans[::-1]


from sys import stdin


def main():
    # 入力
    readline = stdin.readline
    n = int(readline())
    alp = [chr(i) for i in range(97, 97 + 26)]
    m = to_n(n, 26)
    ans = [alp[m[i]] for i in range(len(m))]
    print(("".join(ans)))


if __name__ == "__main__":
    main()

def to_n(x, n, cnt):
    ans = []
    for _ in range(cnt):
        ans.append(x % n)
        x //= n
    return ans[::-1]


from sys import stdin


def main():
    # 入力
    readline = stdin.readline
    n = int(readline())
    alp = [chr(i) for i in range(97, 97 + 26)]
    tmp = 26
    cnt = 1
    while n > tmp:
        n -= tmp
        tmp *= 26
        cnt += 1
    n -= 1
    m = to_n(n, 26, cnt)
    ans = "".join([alp[m[i]] for i in range(len(m))])
    print(ans)


if __name__ == "__main__":
    main()

-def to_n(x, n): +def to_n(x, n, cnt): -    if x == 0: -        return [0] -    while x > 0: -        x -= 1 +    for _ in range(cnt): -    m = to_n(n, 26) -    ans = [alp[m[i]] for i in range(len(m))] -    print(("".join(ans))) +    tmp = 26 +    cnt = 1 +    while n > tmp: +        n -= tmp +        tmp *= 26 +        cnt += 1 +    n -= 1 +    m = to_n(n, 26, cnt) +    ans = "".join([alp[m[i]] for i in range(len(m))]) +    print(ans)