#include <bits/stdc++.h>
using namespace std;
int query(string q);
int cur;
string guess(int n, int s){
vector<char> chars;
for(int i = 0;i < s;i++) chars.push_back('a' + i);
string tree[2*s];
for(int i = 0;i < s;i++){
string S = "";
int pre = 0;
while(true){
S += chars[i];
cur = query(S);
if(pre == cur) break;
pre = cur;
}
S.pop_back();
tree[s+i] = S;
}
for(int i = s-1;i >= 1;i--){
string L = tree[i<<1]; string R = tree[i<<1|1];
int cnt = R.size();
vector<int> pos[R.size()+1];
int p = 0;
for(int l = 0;l < (int) L.size();){
string S;
if(p == (int) R.size()){
for(int j = l;j < (int) L.size();j++) pos[p].push_back(j);
break;
}
cnt++;
pos[p].push_back(l);
for(int j = 0;j < (int) R.size();j++){
for(int c : pos[j]){
S += L[c];
}
S += R[j];
}
cur = query(S);
//cout << cnt << "\n";
if(cur != cnt){
pos[p].pop_back();
p++;
cnt--;
}
else{
l++;
}
}
string S;
for(int j = 0;j <= (int) R.size();j++){
for(int c : pos[j]){
S += L[c];
}
if(j != (int) R.size()) S += R[j];
}
//cout << i << " " << S << "\n";
tree[i] = S;
}
return tree[1];
}
