import sys
input = sys.stdin.readline

def calc(N,x):
    #print(N,x)
    if N==0:
        return []
    if N==1:
        return [x]
    if N%2==1:
        return [x]+calc(N-1,x+1)

    two=0
    k=N
    while k%2==0:
        two+=1
        k//=2

    if k==1:
        return [x]*(two)
    else:
        return [x]*(two+1)+calc(k-1,x+1)

#print(calc(25,1))

N=int(input())

ANS=calc(N,1)

ANS=ANS+ANS[::-1]

for i in range(len(ANS)):
    ANS[i]=chr(ANS[i]+96)

print("".join(ANS))