# 先頭から長さ4の部分文字列を確定させることを考える
# 他の部分は固定して、先頭だけaaaaからzzzzまで26通り試すことで先頭4文字に含まれる英子文字がわかる(順番はまだわからない)
# ↑でわかった英子文字でつくれる候補を全通り(4文字の場合、4種なら4!、3種なら3×(4!/2)、2種なら2×(4!/3!)+2×(4!/2!2!)、1種なら1)調べれば位置もわかる
# これを末尾まで繰り返すことで最大でも(26+36)*(100/4)クエリでできそう
import collections
import itertools
def count_match(s1, s2="gga"):
    cnt = 0
    for i in range(len(s1)):
        if s1[i]==s2[i]:
            cnt += 1
    return cnt

N = int(input())
abc = [chr(ord("a")+i) for i in range(26)]
s = "x"*N
for i in range((N+3)//4):
    if N%4!=0 and i==(N+3)//4-1:
        chnum = N%4
    else:
        chnum = 4
    r1 = {}
    for ch in abc:
        s = s[:4*i] + ch*chnum + s[4*(i+1):]
        print("? "+s)
        r1[ch] = int(input())
        #r1[ch] = count_match(s)
    matched = collections.Counter(r1.values()).most_common()

    cands = []
    for c in matched[1:]:
        for k, v in r1.items():
            if c[0]==v:
                cands.append(k)
    
    if len(cands)==4:
        perm = ["".join(p) for p in list(itertools.permutations(cands))]
    elif len(cands)==3:
        perm = []
        if chnum==4:
            for c in cands:
                perm += list(set(["".join(p) for p in list(itertools.permutations(list(cands)+[c,]))]))
        else:
            perm = ["".join(p) for p in list(itertools.permutations(cands))]
    elif len(cands)==2:
        perm = []
        if chnum==4:
            for c in cands:
                perm += list(set(["".join(p) for p in list(itertools.permutations(list(cands)+[c,c,]))]))
            perm += list(set(["".join(p) for p in list(itertools.permutations(list(cands)+list(cands)))]))
        elif chnum==3:
            for c in cands:
                perm += list(set(["".join(p) for p in list(itertools.permutations(list(cands)+[c,]))]))
        else:
            perm = ["".join(p) for p in list(itertools.permutations(cands))]
    else:
        perm = [cands[0]*chnum]

    ans = ""
    max_match = 0
    for p in perm:
        print("? "+s[:4*i] + p + s[4*(i+1):])
        matched = int(input())
        #matched = count_match(s[:4*i] + p + s[4*(i+1):])
        if matched > max_match:
            ans = p
            max_match = matched
    s = s[:4*i] + ans + s[4*(i+1):]

print("! "+s)