import sys
input = lambda : sys.stdin.readline().rstrip()

write = lambda x: sys.stdout.write(x+"\n")
debug = lambda x: sys.stderr.write(x+"\n")
writef = lambda x: print("{:.12f}".format(x))


n = int(input())
def main(n):
    n0 = n
    ll = []
    while n>2:
        ll.append(n%2)
        if n%2:
            n -= 1
        else:
            n = (n-2)//2
    c = 0
    ans = [c]
    l = []
    for item in ll[::-1]:
        c += 1
        c %= 26
        if not item:
            l.extend([c,c])
        else:
            l.extend([c])
    l = l[::-1]
    if n==1:
        ans = [0]
    else:
        ans = [0,0]
    ans = l + ans + l[::-1]
    ans = "".join(map(lambda c: chr(c+ord("a")), ans))
    return ans
ans = main(n)
print(ans)