v = list("abcdefghijklmnopqrstuvwxy")
n = int(input())
i = 0
r = []
def dfs(n):
    if n==1: return 0
    i = dfs(n//2)
    r.append(v[i])
    if n%2:
        i+=1
        if i > 24: i = 0
        r.append(v[i])
    return i
dfs(n)
r = "".join(r)
s = r[::-1]+"a"+r
print(s)