N=int(input())
S="a"
bottom=""
alpha="abcdefghijklmnopqrstuvwxyz"

for i in range(N):
    if i>25:
        bottom=bottom+"z"
    else:
        bottom=bottom+alpha[i]
    S=S+"a"
print(bottom)

C=0
S=""
def F(S,loop,N,C):
    for i in range(0,loop):
        if N==C+1:
            print(S+bottom[i])
        else:
            F(S+bottom[i],i+2,L,C+1)
    return None
            
F(S,1,L,C)