N = int(input())
S = [0]*N
for i in range(97,123,2):
    a = chr(i)
    b = chr(i+1)
    T = "a"*N
    print("?",T)
    na = int(input())
    for j in range(N):
        T1 = T[:j]+b+T[j+1:]
        print("?",T1)
        nb = int(input())
        if nb==na+1:
            S[j] = b
        elif nb==na-1:
            S[j] = a
print("!","".join(S))