#include <bits/stdc++.h>
using namespace std;

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

    int N; cin >> N;
    string s(N,'a');
    int S;
    cout << "? " << s << endl;
    cin >> S;
    string answer = "";
    for(int i=0; i<N; i++){
        bool add = false;
        for(char c='b'; c<='y'; c++){
            s.at(i) = c;
            cout << "? " << s << endl;
            int now; cin >> now;
            if(S == now+1){
                add = true;
                answer += 'a'; break;
            }
            if(now == S+1){
                add = true;
                answer += c; break;
            }
        }
        if(add == false) answer += 'z';
        s.at(i) = 'a';
    }
    cout << "! " << answer << endl;
}