#include <stdio.h>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using mint = modint998244353;
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf32 1000000001
#define Inf64 1000000000000000001
int query(string s){
	cout<<"? "<<s<<endl;
	int x;
	cin>>x;
	return x;
}

int main(){
	int n;
	cin>>n;
	string ans(n,'a');
	
	rep(i,n){
		vector<int> ret(25);
		rep(j,25){
			ans[i] = 'a'+j;
			ret[j] = query(ans);
		}
		if(ret==vector<int>(25,ret[0])) ans[i] = 'z';
		else ans[i] = 'a'+max_element(ret.begin(),ret.end())-ret.begin();
	}
	cout<<"! "<<ans<<endl;
	
	return 0;
}