import math



# one = 1000000000000001

dict={1:"a",2:"b",3:"c",4:"d",5:"e",6:"f",7:"g",8:"h",9:"i",10:"j",

        11:"k",12:"l",13:"m",14:"n",15:"o",16:"p",17:"q",18:"r",19:"s",20:"t",

        21:"u",22:"v",23:"w",24:"x",25:"y",26:"z"}



n=int(eval(input()))



ans = str(dict[(n-1)%26+1])



n=(n-1)//26

while n:

    ans = str(dict[(n-1)%26+1]) + ans

    n=(n-1)//26



print(ans)

import math



# one = 1000000000000001

dict={1:"a",2:"b",3:"c",4:"d",5:"e",6:"f",7:"g",8:"h",9:"i",10:"j",

        11:"k",12:"l",13:"m",14:"n",15:"o",16:"p",17:"q",18:"r",19:"s",20:"t",

        21:"u",22:"v",23:"w",24:"x",25:"y",26:"z"}



n=int(eval(input()))

ans = ""



while n:

    ans = str(dict[(n-1)%26+1]) + ans

    n=(n-1)//26



print(ans)

import math

# one = 1000000000000001
dict = {
    1: "a",
    2: "b",
    3: "c",
    4: "d",
    5: "e",
    6: "f",
    7: "g",
    8: "h",
    9: "i",
    10: "j",
    11: "k",
    12: "l",
    13: "m",
    14: "n",
    15: "o",
    16: "p",
    17: "q",
    18: "r",
    19: "s",
    20: "t",
    21: "u",
    22: "v",
    23: "w",
    24: "x",
    25: "y",
    26: "z",
}
n = int(eval(input()))
ans = str(dict[(n - 1) % 26 + 1])
n = (n - 1) // 26
while n:
    ans = str(dict[(n - 1) % 26 + 1]) + ans
    n = (n - 1) // 26
print(ans)

import math

# one = 1000000000000001
dict = {
    1: "a",
    2: "b",
    3: "c",
    4: "d",
    5: "e",
    6: "f",
    7: "g",
    8: "h",
    9: "i",
    10: "j",
    11: "k",
    12: "l",
    13: "m",
    14: "n",
    15: "o",
    16: "p",
    17: "q",
    18: "r",
    19: "s",
    20: "t",
    21: "u",
    22: "v",
    23: "w",
    24: "x",
    25: "y",
    26: "z",
}
n = int(eval(input()))
ans = ""
while n:
    ans = str(dict[(n - 1) % 26 + 1]) + ans
    n = (n - 1) // 26
print(ans)

-ans = str(dict[(n - 1) % 26 + 1]) -n = (n - 1) // 26 +ans = ""