LIST=[0,1,2]
for i in range(10**6):
    LIST.append(LIST[-1]+1+(len(LIST)-1)//2)

N=int(input())

ANS=[]
c=0
while N>0:
    for i in range(len(LIST)):
        if LIST[i]<=N:
            plus=i
        else:
            break
    ANS+=[c,c+1]*(plus//2)
    if plus%2==1:
        ANS.append(c)
    c+=2

    N-=LIST[plus]

ANS=[chr(ANS[i]+97) for i in range(len(ANS))]

print("".join(ANS))