#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
typedef long long ll;
using namespace __gnu_pbds;
using namespace std;
template <typename T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
int query(string str);
int N;
int getQ(string s) {
if(s.size() > N) return N+20;
return query(s);
}
string cdq(int n, int S, string doklej) {
N=n;
if(n==0) return doklej;
vector<int> cnt(S);
string alph = "abcdefghijklmnopqrstuvwxyz";
vector<int> V;
for(int i=0; i<S; ++i) {
string s = "";
s.push_back(alph[i]);
while(getQ(s+doklej)==s.size()) s.push_back(alph[i]);
cnt[i] = s.size() - 1;
if(cnt[i]) V.push_back(i);
}
sort(V.begin(), V.end(), [&](int a, int b){
string s(cnt[a], alph[a]);
s.push_back(alph[b]);
if(getQ(s+doklej)==s.size()) return true;
return false;
});
vector<int> bloki;
for(int i=V.size()-1; i>=0; --i) {
if(i==0) bloki.push_back(cnt[V[i]]);
else {
int v = V[i];
int u = V[i-1];
int lo = 1;
int hi = n;
while(lo < hi) {
string s = "";
for(int x=0; x<cnt[u]; ++x) s.push_back(alph[u]);
int mid = (lo+hi+1)/2;
for(int x=0;x<mid;++x) s.push_back(alph[v]);
if(getQ(s+doklej)==s.size()) lo = mid;
else hi=mid-1;
}
bloki.push_back(lo);
}
}
reverse(bloki.begin(), bloki.end());
string res = "", stos="";
for(int i=0; i<bloki.size(); ++i) for(int x=0; x<bloki[i]; ++x) res.push_back(alph[V[i]]);
for(int i=res.size(); i>=0; --i) {
int failed=0;
for(int lit=0; lit<S; ++lit) {
string old_res = res;
stos = "";
for(int x=res.size()-1; x>=i; --x) {
stos.push_back(res[x]);
res.pop_back();
}
reverse(stos.begin(), stos.end());
res.push_back(alph[lit]);
res += stos;
if(getQ(res)!=res.size()) {
res = old_res;
failed++;
} else i++;
}
if(failed < S) ++i;
}
return res;
return cdq(n-res.size(), S, res);
}
string guess(int n, int S) {
return cdq(n,S,"");
}
