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

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    int n;
    cin >> n;
    auto ask = [&](string &ans){
        int v;
        cout << "? " << ans << endl;
        cin >> v;
        return v;
    };
    string ans, t(n, 'a');
    for(int i = 0; i < n; i++){
        vector<pair<char, int>> pos(25);
        for(int j = 0; j < 25; j++){
            t[i] = j + 'a';
            pos[j] = make_pair(ask(t), j + 'a');
        }
        sort(pos.rbegin(), pos.rend());
        if(pos[0].first > pos[1].first){
            ans += pos[0].second;
        }else{
            ans += 'z';
        }
    }
    cout << "! " << ans << endl;
}