

def resolve():

    lower = "abcdefghijklmnopqrstuvwxyz"

    N = int(eval(input()))    



    ans = ""

    while N > 26:

        idx = N % 26

        ans += lower[idx-1]

        N = -(-N//26)-1

    idx = N % 26

    ans += lower[idx - 1]

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



if __name__ == "__main__":

    resolve()



def resolve():

    lower = "abcdefghijklmnopqrstuvwxyz"

    N = int(eval(input()))



    ans = ""

    while N:

        N -= 1

        idx = N%26

        ans += lower[idx]

        N //= 26

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



if __name__ == "__main__":

    resolve()

def resolve():
    lower = "abcdefghijklmnopqrstuvwxyz"
    N = int(eval(input()))
    ans = ""
    while N > 26:
        idx = N % 26
        ans += lower[idx - 1]
        N = -(-N // 26) - 1
    idx = N % 26
    ans += lower[idx - 1]
    print((ans[::-1]))


if __name__ == "__main__":
    resolve()

def resolve():
    lower = "abcdefghijklmnopqrstuvwxyz"
    N = int(eval(input()))
    ans = ""
    while N:
        N -= 1
        idx = N % 26
        ans += lower[idx]
        N //= 26
    print((ans[::-1]))


if __name__ == "__main__":
    resolve()

-    while N > 26: +    while N: +        N -= 1 -        ans += lower[idx - 1] -        N = -(-N // 26) - 1 -    idx = N % 26 -    ans += lower[idx - 1] +        ans += lower[idx] +        N //= 26