#include <bits/stdc++.h>

using namespace std;
using ll = long long;

void query(string &S){
    cout << "? " << S << endl;
}
void answer(string &T){
    cout << "! " << T << endl;
}

int main(){
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);

    int N, q, r, n;
    cin >> N;
    q = N / 3;
    r = N % 3;

    string S = string(N, 'a');

    for (int i=0; i<q; i++){
        vector<pair<int, int>> a(26);
        for (int j=0; j<26; j++){
            S[i*3] = char(j+'a');
            S[i*3+1] = char(j+'a');
            S[i*3+2] = char(j+'a');
            query(S);
            cin >> n;
            a[j] = {n, j};
        }
        sort(a.rbegin(), a.rend());
        if (a[0].first == a.back().first+3){
            S[i*3] = char(a[0].second+'a');
            S[i*3+1] = char(a[0].second+'a');
            S[i*3+2] = char(a[0].second+'a');
        }
        else if (a[0].first == a.back().first+2){
            assert(a[1].first == a.back().first+1);
            for (int j=0; j<3; j++){
                S[i*3] = char(a[0].second+'a');
                S[i*3+1] = char(a[0].second+'a');
                S[i*3+2] = char(a[0].second+'a');
                S[i*3+j] = char(a[1].second+'a');
                query(S);
                cin >> n;
                if (n == a.back().first+3){
                    break;
                }
            }
        }
        else{
            assert(a[0].first == a.back().first+1);
            assert(a[1].first == a.back().first+1);
            assert(a[2].first == a.back().first+1);
            vector<int> v = {0,1,2};
            do{
                S[i*3] = char(a[v[0]].second+'a');
                S[i*3+1] = char(a[v[1]].second+'a');
                S[i*3+2] = char(a[v[2]].second+'a');
                query(S);
                cin >> n;
                if (n == a.back().first+3){
                    break;
                }
            } while(next_permutation(v.begin(), v.end()));
        }
    }

    for (int i=0; i<r; i++){
        vector<pair<int, int>> a(26);
        for (int j=0; j<26; j++){
            S[N-1-i] = char(j+'a');
            query(S);
            cin >> n;
            a[j] = {n, j};
        }
        sort(a.rbegin(), a.rend());
        S[N-1-i] = char(a[0].second+'a');
    }

    answer(S);

    return 0;
}