#include <bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;
#define ll long long
#define rep(i, n) for (ll i = 0; i < (ll)(n); i++)
//using mint = modint998244353;
const int dx[4]={0,1,0,-1};
const int dy[4]={1,0,-1,0};

int n;
int ok[111];
int main(){
    cin>>n;
    string ans="";
    rep(i,n)ans.push_back('a');
    int cnt=2500;
    cout<<"? "<<ans<<endl;
    int x;
    cin>>x;
    cnt--;
    int now=x;
    rep(j,26){
        rep(i,n){  
            if(cnt<=0)break;  
            if(ok[i])continue;
            string t=ans;
            t[i]=(char)('a'+j);
            cout<<"? "<<t<<endl;
            int x;
            cin>>x;
            cnt--;
            if(x-now==1){
                ok[i]=1;
                now=x;
                ans=t;
            }
        }
        if(now==x)break;
    }
    if(now!=x)rep(i,n)if(ok[i]==0)ans[i]='z';
    cout<<"! "<<ans<<endl;
    return 0;
}