N=int(input())
ans=["a"]*N

for i in range(N):
  x=0
  tmp=0
  flag=0
  for j in range(26):
    ans[i]=chr(97+j)
    t="".join(ans)
    print("?",t,flush=1)
    n=int(input())
    if n>x:
      x=n
      tmp=j
      if flag:
        break
      flag=1
  ans[i]=chr(97+j)

print("!","".join(ans))