def cs(b,s,N):
	for i in xrange(1,N+1):
		if C[i+1] <= N:
			continue
		return N-C[i], s+[chr(b+(j&1)) for j in range(2*i-1)]
	return 0, s
N = int(raw_input())
C = [i**2 for i in xrange(1<<15)]
N,s = cs(97,[],N)
N,s = cs(99,s,N)
print "".join(s+[chr(101+(k%22)) for k in xrange(N)])