#include <bits/stdc++.h>
using namespace std;
int main() {
map<string, bool> used;
string S = "a";
int k;
cin >> k;
for(int j = 1; ; j += 1){
for(int i = 0; i < k; i += 1){
string current = "aa";
current[0] = S.back();
current[1] = char('a' + i);
if(!used[current]){
S += char('a' + i);
used[current] = true;
break;
}
}
if(S.size() != j+1) break;
}
cout << S;
return 0;
}
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