N = int(eval(input()))

lis = [0,26]

num = 26

n = 1

while lis[-1]<N:

    num *= 26

    lis.append(lis[-1]+num)

    n += 1

c = N-lis[-2]-1

ans = ''

for i in range(n):

    ans = chr(c%26+ord('a')) + ans

    c //= 26

print(ans)
def solve():

  N = int(eval(input()))

  k = 1

  while N>pow(26,k):

    N -= pow(26,k)

    k += 1

  ans = ''

  N -= 1

  for i in range(k,0,-1):

    if i>1:

      ans += chr(ord('a')+N//pow(26,i-1))

    else:

      ans += chr(ord('a')+N%pow(26,i))

    N%=pow(26,i-1)

  return ans

print((solve()))
N = int(eval(input()))
lis = [0, 26]
num = 26
n = 1
while lis[-1] < N:
    num *= 26
    lis.append(lis[-1] + num)
    n += 1
c = N - lis[-2] - 1
ans = ""
for i in range(n):
    ans = chr(c % 26 + ord("a")) + ans
    c //= 26
print(ans)

def solve():
    N = int(eval(input()))
    k = 1
    while N > pow(26, k):
        N -= pow(26, k)
        k += 1
    ans = ""
    N -= 1
    for i in range(k, 0, -1):
        if i > 1:
            ans += chr(ord("a") + N // pow(26, i - 1))
        else:
            ans += chr(ord("a") + N % pow(26, i))
        N %= pow(26, i - 1)
    return ans


print((solve()))

-N = int(eval(input())) -lis = [0, 26] -num = 26 -n = 1 -while lis[-1] < N: -    num *= 26 -    lis.append(lis[-1] + num) -    n += 1 -c = N - lis[-2] - 1 -ans = "" -for i in range(n): -    ans = chr(c % 26 + ord("a")) + ans -    c //= 26 -print(ans) +def solve(): +    N = int(eval(input())) +    k = 1 +    while N > pow(26, k): +        N -= pow(26, k) +        k += 1 +    ans = "" +    N -= 1 +    for i in range(k, 0, -1): +        if i > 1: +            ans += chr(ord("a") + N // pow(26, i - 1)) +        else: +            ans += chr(ord("a") + N % pow(26, i)) +        N %= pow(26, i - 1) +    return ans + + +print((solve()))